Modern Refrigeration and

1
Modern Refrigeration and Air Conditioning
Althouse Turnquist Bracciano
PowerPoint Presentation by Associated
Technical Authors
PublisherThe Goodheart-Willcox Company,
Inc.Tinley Park, Illinois
2
Chapter 12
Servicing and Installing Small Hermetic Systems
3
Learning Objectives

• Select proper tools and instruments needed for
  installing or servicing domestic and small
  commercial systems.
• List supplies needed on a typical installation or
  service call.
• Service internal and external mechanisms using
  the proper tools and materials.
• Locate areas causing noise and make necessary
  adjustments to the system.

4
Learning Objectives

• Recognize trouble signals.
• List common external service operations.
• Start a stuck compressor.
• Demonstrate proper use of piercing valves.
• Check for restrictions in the system.
• Troubleshoot common refrigeration problems.

5
Learning Objectives

• Use the proper methods and equipment for checking
  electrical systems of refrigerators and freezers.
• Follow approved safety procedures.

6
Refrigerants

• R-12 was the primary refrigerant used in domestic
  refrigerators and freezers for most of the
  twentieth century.
• As of 1996, R-12 is no longer manufactured.
• R-134a is now the primary refrigerant used in
  domestic equipment. However, units with R-12 will
  be operational for years to come and will require
  repair.

7
Instruments, Tools and Supplies
12.1.1

• Instruments needed for refrigeration service
  work
• Pressure recorder.
• Temperature recorder.
• Off-On recorder.
• Watt recorder.
• Electronic sound tracer.
• Electronic leak detector.
• Compound gauge.
• Pressure gauge.

8
Instruments, Tools and Suppliescontinued
12..1.1

• Instruments needed for refrigeration service
  work
• Thermometer with a range of 20ºF to 212ºF
  (29ºC to 100ºC).
• Voltmeter.
• Ammeter.
• Ohmmeter.
• Test light (incandescent, 120V, 100W).

9
Refrigerant Tools
12..1.2

• High-vacuum pump.
• Recovery/recycling unit.
• Service cylinders for R-12, R-22, R-502, and
  R-134a.
• Purging line (1/4" diameter by 15', equipped with
  hand shut-off needle valve and check valve).
• Capillary tube cleaner.
• Capillary tube sizing kit.
• Soldering-brazing torch (LP fuel-air,
  acetylene-air, or oxyacetylene).

10
Refrigerant Toolscontinued
12..1.2

• Hand vacuum cleaner.
• Gauge manifold.
• Process tube adaptors.
• Bending springs.

11
Wrenches
12..1.2

• Set of 3/8" drive sockets (12 point, 7/16" to
  1"), with 3/8" drive torque handle, speed handle,
  swivel handle, and T-handle.
• Adjustable open-end wrenches (8").
• Set of Allen setscrew wrenches.
• Refrigeration ratchet wrench3/16", 7/32", and
  1/4"with square openings.
• Set of 15º open-end wrenches (1/2", 3/4", 7/8",
  and 1").
• Box-end wrench (1/2").
• T-socket wrench (1/2").

12
More Tools
12..1.2

• Pliers
• Combination (6").
• Wire cutter.
• Slim nose.
• Hammers
• Claw hammer.
• Rubber mallet.

13
Tubing Tools
12..1.2

• Bending springs for 1/4", 3/8", and 1/2" OD
  tubing.
• Flaring tool (3/16" to 1/2" capacity).
• Tubing cutter.
• Pinch-off tool.
• Swaging tool.

14
Screwdrivers
12..1.2

• Standard screwdrivers (3", 6", and 8") with
  insulated handles.
• Phillips screwdrivers (3", 6", and 8") with
  insulated handles.

15
Supplies
12..1.3

• Wire solders (60/40 and 95/5).
• Soldering flux.
• Silver brazing wire (3060 silver no cadmium).
• Phosphorous-copper alloy wire.
• Brazing flux.
• Steel wool.
• Medium-grade sandpaper.
• Plastic tape.
• Refrigerant recovery unit.

16
Suppliescontinued
12..1.3

• Disposable cylinders of refrigerant.
• Coils of soft copper tubing (1/4", 5/16", 3/8",
  and 1/2").
• Copper pipe (as needed).
• Capillary tubing.
• Filter-drier cartridges.
• Refrigerant oil (150 and 300 viscosity).
• Refrigerant oil can (spout type).
• Cleaning cloths.

17
Suppliescontinued
12..1.3

• Relays.
• Capacitors.
• Motor controls.
• Refrigerant controls.
• Overload protectors.
• Light switches.
• Sealing compounds.
• Driers (flared and soldered fittings).
• Filter-driers (flared and soldered fittings).

18
Suppliescontinued
12..1.3

• Sight glasses (flared and soldered fittings).
• Flared fittings (SAEall sizes and shapes).
• Piercing valves and valve adaptors.
• Valve cores.

19
Installing Refrigeratorsand Freezers
12.2

• Correct installation ensures proper operation of
  a refrigerator or freezer.
• Units are shipped with full written instructions.

20
Uncrating aRefrigerator or Freezer
12.2.1

• Carefully follow the directions in the crate.
• Areas of the cabinet may be easily damaged in
  moving or uncrating. They include
• BottomCondensing unit.
• BackCondenser may be damaged.
• DoorMay be forced out of alignment or buckled.
• Compressor domes may be shipped with either
  removable shipping bolts or loosened dome
  shipping bolts.

21
Uncrating aRefrigerator or Freezer
12.2.1
A hand-truck may be used to aid in moving the
appliance.
22
Properly Positioning a Refrigerator-Freezer
12.2.2

• Do not locate refrigerator-freezer in direct
  sunlight or near an oven, warm air register, or
  other heat source.
• The room should be large enough to provide proper
  air flow to cool the condenser.

23
Electrical Supply
12.2.3

• Check the electrical rating on the appliance
  against the electrical supply provided at the
  wall outlet.
• There should be a separate circuit from the fuse
  or circuit breaker box to the refrigerator-freezer
  outlet.
• Do not use an extension cord between the power
  cord and wall outlet resulting voltage may be
  too low.
• Voltage at refrigerator outlet can be checked
  with a voltmeter or multimeter.

24
Electrical Supply
12.2.3
25
Electrical Supplycontinued
12.2.3

• If the voltage at the refrigerator outlet drops
  more than 10V when starting, the wiring in the
  circuit is not heavy enough. A flicker in the
  lights at the moment of starting is a sign of
  poor electrical supply.
• If the wall outlet has a three-prong socket and
  the unit has a matching power cord plug, there is
  grounding. If not, a wire must be attached
  between a metal part of the cabinet and a good
  ground, such as a water pipe.

26
Electrical Supplycontinued
12.2.3

• CautionAlways check for proper grounding in the
  outlet box supplying current to the unit being
  serviced. Take a voltmeter reading from the
  live wall receptacle connection to the
  receptacle ground connection. A full voltage
  reading indicates the outlet is properly grounded.

27
Providing Proper Ventilation
12.2.4

• In installations where there is inadequate space
  for air movement, cooling fans must be used.
• Units with a shroud covering the condenser must
  have air circulation at the bottom, back, and
  top.
• Units that use the outside shell as the condenser
  surface must have at least 2" (51mm) of space
  between the surrounding cabinet and surfaces.
• A spirit level should be used during installation
  to ensure correct leveling.

28
Providing Proper Ventilationcontinued
12.2.4
Front supports are usually adjustable.
29
Starting a Refrigerator-Freezer
12.2.5

• Test the wall outlet with voltmeter to determine
  presence of electrical power.
• Put the temperature control in the off position.
• Connect the electrical cord to the wall outlet.
• Test the unit for operation prior to moving it
  into position.
• Set the temperature control at the middle range.
  After a few hours of operation, check the
  thermometer in the refrigerator compartment.
  Adjust the temperature control setting as needed.

30
Starting a Refrigerator-Freezer
12.2.5

• If the unit does not start, check that the
  electrical circuit is in good condition. Next,
  check for mechanical trouble. Open and close the
  doors to make sure the interior lights are
  functioning properly.
• Note If a refrigerator-freezer using a capillary
  tube system refrigerant is stopped and then
  started immediately, it may fail to operate.
  Disconnect the refrigerator for a few minutes.
  Allow the refrigerant pressure time to balance
  between the high and the low sides. Then, start
  the system again.

31
Installing an Ice Cube Maker
12.2.6

• Many domestic refrigerators have automatic ice
  makers. These are connected to a cold water line
  by a coil of 1/4" copper or plastic tubing.
• Prior to putting refrigerator in place, run the
  copper tubing to the nearest cold water line.
  (Cabinet partitions or the floor may need to be
  drilled.) Mount a tap valve on the water line.
• Connect the tubing to the valve. Connect the
  other end of the tubing to the water line
  fitting. Allow several large loops of tubing so
  the unit may be moved out for cleaning and
  servicing.
• Turn the tap valve stem in slowly and pierce the
  cold water pipe. Check for leaks. Gently move the
  unit back into place.

32
Installing an Ice Cube Maker
12.2.6
33
Shutting Down aRefrigerator-Freezer
12.2.7

• When shutting down for a period of time,
  precautions must be taken to prevent rusting and
  remove odor. Remove the plug and switch off
  current. Defrost until unit is completely
  defrosted.
• Remove water from interior. Wash inside of
  cabinet with solution of baking soda and water.
  Thoroughly dry the cabinet.
• Leave the doors or lids slightly ajar to allow
  circulation of air during shutdown period.

34
Shutting Down aRefrigerator-Freezercontinued
12.2.7

• Caution Federal law requires the removal of the
  door(s) from any out-of-service refrigerator or
  freezer. Children can suffocate when hiding or
  playing in a discarded unit! When taking a
  refrigerator or freezer out of service, always
  remove the cabinet door(s).

35
Troubleshooting the Hermetic Refrigerator-Freezer
12.3

• Potential complaints of unsatisfactory
  performance
• Refrigerator does not run.
• Refrigerator runs all the time temperatures are
  too cold.
• Refrigerator runs all the time temperatures are
  too warm.
• Refrigerator runs all the time temperatures are
  satisfactory.
• Refrigerator cycles, but food compartment is too
  warm freezing compartment is satisfactory.

36
Troubleshooting the Hermetic Refrigerator-Freezer
continued
12.3

• Potential complaints of unsatisfactory
  performance
• Refrigerator cycles, but freezing compartment is
  too cold.
• Motor control cuts out.
• Refrigerator cycles satisfactorily refrigeration
  is poor.
• Refrigerator cycles, but does not freeze ice
  cubes.
• Refrigerator cycles, but too much ice accumulates
  on the evaporator.
• Refrigerator mechanism is very noisy.

37
Ice on the Evaporator
12.3.1

• Large ice buildup in food storage space results
  in poor cooling. Cause is usually a leaky door
  seal (gasket).
• In a frost-free or automatic defrost
  refrigerator, frost buildup indicates defrost is
  not operating.
• Refrigerators with a separate freezer compartment
  door often have an electric heater around the
  door opening. This is referred to as a mullion
  heater. The mullion heater prevents ice or
  moisture from forming around the door opening.
• Insert a thin piece of paper between the door and
  cabinet. It should hold tightly when the door is
  closed. If it can be pulled out easily, the
  gasket needs to be replaced.

38
Moisture and Icein the Cabinet Insulation
12.3.2

• Moisture and ice in the insulation indicates an
  air leak in the outside cabinet seal or shell.
  Wet insulation will lose its heat-insulating
  qualities.
• Two indicators of moisture in the insulation are
• Condensing unit will run more often than normal.
• Outside surface of the refrigerator will feel
  colder than normal wherever insulation is wet.
• Most freezers provide a small opening through the
  inner lining, connecting the insulated area with
  the inside of the freezer cabinet. Moisture will
  tend to escape through this opening and condense
  on the evaporator surface.

39
Temperature-Pressure Conditions
12.3.3

• Prior to servicing a refrigerator, you must know
• Normal temperature in the evaporator during the
  operating cycle.
• Normal pressure on the low-pressure side during
  the operating cycle.
• Normal temperature of the condenser during the
  operating cycle.
• Normal pressure on the high-pressure side during
  the operating cycle.

40
Temperature-Pressure Conditionscontinued
12.3.3
A temperature recorder using vapor-filled bulbs
may be used to test operating temperatures.
41
Temperature-Pressure Conditionscontinued
12.3.3
A high-pressure gauge and compound gauge may be
used to determine the operating pressures.
42
Locating and Eliminating Noises
12.3.4

• Noises in the refrigerator usually come from
  rattles. Sources may include
• Loose baffles or ducts.
• Tubing touching something while vibrating.
• A tilting of the condensing unit caused by an
  uneven floor.
• Fan and motor vibration.
• A loose evaporator unit door.
• Loose articles on shelves.
• Shelves not seated properly on supports.

43
Locating and Eliminating Noisescontinued
12.3.4
An ultrasonic leak detector may be used to
isolate many noises. ASensor.BDisplay.CSensit
ivity dial.DEarphone.
44
Locating and Eliminating Noisescontinued
12.3.4

• Noise from within the unit may indicate it is
  laboring too hard.
• To determine this, test the electrical load with
  an ammeter or wattmeter.
• Three seconds is the average time to operate a
  relay on starting. A slower start indicates an
  overload.

45
Locating and Eliminating Noisescontinued
12.3.4
A vibration or hum may be reduced by carefully
bending the tubing away from contact or clamping
rubber blocks on the tubing.
46
Locating and Eliminating Noisescontinued
12.3.4

• Loose baffles and ducts can be secured with
  self-tapping sheet metal screws.
• Pressure sensitive tapes provide protection
  against moisture, heat, sound, and
  electromagnetic waves.

47
Locating and Eliminating Noisescontinued
12.3.4
An inspection mirror is often needed to see into
hard-to-reach places.
48
Cycling Timefor Refrigerators and Freezers
12.3.5

• Cycling times for residential refrigerators and
  freezers vary depending on a number of factors
  including amount of storage space being used,
  outside box temperature, and compressor
  condition.
• Any unusual change in cycling time should be
  investigated immediately.

49
Hermetic Servicing
12.4

• Check all performance data information prior to
  servicing a unit. Usually located on the
  identification plate mounted on the compressor,
  information will include
• Type of refrigerant.
• Refrigerant charge.
• Compressor hp.
• Compressor speed.
• Running amperes.
• Voltage.
• Phase.
• Other items.

50
Hermetic Servicing
12.4
Chart showing operating characteristics.
51
Hermetic Servicingcontinued
12.4

• Servicing of hermetic refrigerators includes
• External servicing.
• Internal servicing.
• Overhaul of hermetic systems.

52
External Servicing Operations
12.5

• External servicing operations may include
• Cabinet hardware.
• Ice cube maker.
• Cleaning.
• Eliminating noise (rattle).

53
External Servicing Operationscontinued
12.5

• External servicing operations may include
• Electrical.
• Power-in circuit.
• Thermostat.
• Defrost thermostat.
• Interior light and circuit.
• Fan motor and circuit.
• Damper controls.
• Motor compressor (relay and overload protector,
  capacitor, or motor terminals).

54
External Servicing Operationscontinued
12.5

• External servicing operations may include
• Defroster.
• Defroster control and circuit.
• Defroster heater coil.
• Cabinet heaters.
• Evaporator fan and circuit.
• Condenser fan and circuit.
• Light circuit.
• Butter conditioner circuit.

55
External Servicing Operationscontinued
12.5
External mechanisms, electrical wiring, and
electrical parts can all be checked for operation
quickly usinga volt-amp-ohmmeter or multimeter.
56
External Servicing Operationscontinued
12.5

• Additional external service troubles can be
  located by checking for
• Ice on evaporator.
• Frost or sweat on suction line.
• Warm or hot discharge line.
• Ice or sweat on driers.
• Dirty condensers.

57
Diagnosing External Troubles
12.5.1

• Carefully check the following parts of the
  external electrical circuit prior to replacing a
  hermetic compressor
• Power-in connections.
• Thermostat.
• Wire terminals.
• Relay.
• Capacitor (if unit has one).

58
Diagnosing External Troublescontinued
12.5.1

• The external electrical components can be checked
  independently by removing them from the system.
  Another method is to temporarily replace the item
  with test part of the proper size. The unit may
  then be checked to see if it will run.
• Electrical connections must be clean and tight.
  If loose or dirty, they may overheat. This high
  temperature will discolor the connection. A blue
  or greenish tint indicates overheating and
  corrosion. If insulation is charred, overheating
  has occurred.

59
Diagnosing External Troublescontinued
12.5.1
A plug-on thermal motor protector protects the
motor from overheating. In addition, a start
relay positive temperature coefficient thermistor
(PTCT) is used.
60
Diagnosing External Troublescontinued
12.5.1

• Conditions such as open circuits and grounded
  electrical wires are easily checked with a
  multimeter.
• A test cord may be used to check four-pole
  motors.
• Two-pole motors may be tested only by using a
  proper size relay in the circuit. These motors
  overheat if starting circuit is connected more
  than two or three seconds.

61
TroubleshootingHermetic Electrical Units
12.5.1

• Check electrical supply.
• Check appliance voltage specifications. Use a
  voltmeter to test the open circuit voltage.
• Plug in appliance and check the voltage while
  unit is running. The open circuit voltage is
  likely to be slightly higher (no more than 5V)
  with the motor running.
• A difference of 10V or more indicates serious
  trouble
• An overload.
• Motor winding damage.
• Poor wiring to wall outlet.

62
TroubleshootingHermetic Electrical
Unitscontinued
12.5.1
Locate the wiring diagram and check each circuit
independently.
63
TroubleshootingHermetic Electrical
Unitscontinued
12.5.1

• If compressor fails to start
• Determine if electricity is reaching the motor
  compressor.
• If it is, check the starting relay and circuit
  protectors.
• Disconnect all wiring from the motor compressor.
• Check the motor compressor with a manual start
  cord. The ground clip must be fastened to the
  dome.
• All clips or connectors should be plastic coated
  to protect from shocks.

64
TroubleshootingHermetic Electrical
Unitscontinued
12.5.1
All clips or connectors should be plastic coated
to protect from shocks.
65
TroubleshootingHermetic Electrical
Unitscontinued
12.5.1

• Press manual switch.
• After one or two seconds, lift the switch button
  to open the starting winding circuit.
• If the motor operates, the problem is in the
  external circuit.

66
TroubleshootingHermetic Electrical
Unitscontinued
12.5.1
Testing a capacitor-start, induction-run motor.
67
TroubleshootingHermetic Electrical
Unitscontinued
12.5.1

• Testing a capacitor-start, induction-run motor
• Replace the capacitor with a new one of the same
  voltage and microfarad rating. An extra clip wire
  or lead is needed.
• Operate the switch as in previous frame.
• If the motor compressor works, check the
  electrical system up to the compressor.
• If the motor does not start, further motor checks
  are needed.

68
TroubleshootingHermetic Electrical
Unitscontinued
12.5.1
69
TroubleshootingHermetic Electrical
Unitscontinued
12.5.1

• Testing a capacitor-start, induction-run motor
• Caution After testing is completed, short the
  testing capacitor using a 20,000W (20kW), 2W
  resistor. This will eliminate possibility of
  electrical shock!
• Test cords can be used for checking continuity
  and grounding by replacing the fuse with a
  lightbulb.
• If trouble is found in evaporator or condenser,
  they should be replaced.

70
Defective Mullion Heater
12.5.1

• A defective mullion heater may cause door gasket
  to freeze to the cabinet.
• Locate the circuit in the wiring diagram.
• Disconnect both ends of the mullion heater leads.
• Test the heater for continuity. If proven
  defective, check for another mullion heater in
  the insulation.
• Test it. If operating properly, install it.
• If there is no additional heater, install a new
  one of the same wattage rating.
• If the problem is a faulty wire, use a stiff
  steel wire to pull new wiring through the
  insulation.

71
Electrical Troubleshooting
12.5.1
The RED system can be used to check electrical
circuits on General Electric products. It checks
circuits for faults in the defrost system,
thermostats, heaters, fans, and
compressor. AMale connector.BFemale connector.
72
Electrical Troubleshootingcontinued
12.5.1
A multiple-circuit connector mounted at the front
bottom of the cabinet is used.
73
Electrical Troubleshootingcontinued
12.5.1

• Always turn the thermostat to the off position
  prior to separating the connector.
• After connecting tester, turn power on. The
  power on light should be lighted. If not, the
  power circuit needs repair.

74
Electrical Troubleshootingcontinued
12.5.1
All Tecumseh motor compressor terminals are set
up to read Common-Start-Run (from left to
right).
75
Electrical Troubleshootingcontinued
12.5.1

• Motor terminal connection may be stamped R, S,
  and C. If they are not identified, measure the
  resistance of the compressor windings.
• First, measure the resistance across each set of
  terminals. The sum of two of the readings should
  equal the third.

76
Electrical Troubleshooting
12.5.1
77
Electrical Troubleshootingcontinued
12.5.1

• Determine which terminal is common. The common
  terminal is the one which does not contain the
  greatest resistance.
• Determine which terminal is the start terminal.
  The start terminal should include the greatest
  resistance between itself and the common.
• The last terminal is the run terminal. Mark the
  final motor terminal locations.

78
Starting a Stuck Compressor
12.5.1

• Three ways to start a stuck compressor
• Disconnect the wiring to the motor compressor.
  Connect test cord into electrical circuit of the
  main winding. Connect an extra capacitor into the
  circuit. Turn on the power from one to three
  seconds. The extra capacitor will try to reverse
  the compression rotation.
• Caution The capacitor cannot be left in the
  circuit more than a second or two or it will
  cause the motor to overheat!

79
Starting a Stuck Compressor
12.5.1

• Three ways to start a stuck compressor
  (continued)
• Connect the 120V motor compressor into a 240V
  power circuit, using a starter cord.
• Caution Press the pushbutton switch for only a
  second at a time to avoid motor damage! The extra
  voltage may break the stuck compressor loose.
• An extra-torque method is to connect a 240V, 100
  microfarad start capacitor across the terminals
  of the run capacitor. The connection must be for
  no more than one second.

80
Short-Cycling
12.5.1

• Short cycling is a term used to describe a unit
  that starts and stops too frequently. Cause may
  be
• Thermostat not mounted securely.
• Loose connections in the starting relays.
• Caution Do not tap a relay to check it! This may
  cause the points to damage the motor.

81
Cleaning theExternal Mechanism
12.5.1

• The condenser and compressor should be cleaned
  every three months. Units with condenser fans
  should be disconnected from electrical power
  prior to cleaning.
• Clean hermetic dome using a vacuum cleaner.
• In the shop, high-pressure air, carbon dioxide,
  or nitrogen may be used for cleaning.
• Caution Goggles should always be used and there
  should be adequate ventilation.

82
Internal Service Operations
12.6

• Internal service includes any of the following
• Removal of any part of the hermetic system.
• Determination of air in the system.
• Discovery of lack of refrigerant.
• Investigation for clogged filter-drier or
  capillary tube.
• Internal service operations require gauges and
  servicing devices. These include vacuum pumps,
  refrigerant cylinders, etc.

83
Internal Service Operationsconditions
12.6

• Prior to opening the system
• Thoroughly clean all connections and valve
  fittings.
• Install a valve adaptor or piercing valve.
• Install a gauge manifold.
• Install refrigerant recovery equipment.

84
Internal Service Operationsconditions
12.6

• The following are the most common service
  operations
• Locating and repairing refrigerant leaks.
• Purging, charging, and recovery of refrigerant.
• Cleaning or replacing the capillary tube.
• Replacing a compressor.
• Replacing a filter-drier on the high side.
• Installing a filter-drier on the low side.
• Evacuating the system.

85
Internal Service Operationsconditions
12.6

• The following are the most common service
  operations performed (continued)
• Adding oil.
• Using a high-vacuum pump.
• Replacing an evaporator and/or condenser.
• NoteSome service operations are best performed
  in the shop.

86
Diagnosing Internal Troubles
12.6.1

• Gauges, thermometers, electrical instruments, and
  careful observation can assist in diagnosing
  internal troubles.
• A partially frosted evaporator, with another part
  heavily frosted, indicates a lack of refrigerant.
• A sweating or frosted suction line indicates
  liquid refrigerant in the suction line. The cause
  may be a broken thermostat or too much
  refrigerant (if a capillary tube is used).

87
Diagnosing Internal Troublescontinued
12.6.1

• Internal electrical troubles involving the motor
  and connections are very rare (3 of 1000 cases!).
  Most internal problems are due to air and
  moisture in the motor compressor causing
  corrosion, and eventually, burnout.
• Liquid refrigerant reaching the compressor may
  remove oil or slug compressor. Valves may be
  broken as the compressor attempts to pump oil or
  liquid refrigerant.
• Continuous running and no refrigeration, and a
  condenser cooler than normal may indicate a
  restriction in the capillary tube or filter-drier
  or screen on the high side.

88
Moisture in theRefrigerant Circuit
12.6.1

• Moisture in the system will cause the unit to
  malfunction. Moisture will form ice in the
  refrigerant control at the point the liquid
  refrigerant is expanding into the evaporator.
  This is noted by the following.
• System will completely defrost. Ice that caused
  the blockage will disappear. Unit will work again
  only until the ice forms again at the refrigerant
  control.
• Pressure will decrease in the suction line.
  Compound gauge shows a steady decrease over
  several hours. Pressure will suddenly become
  normal again. This cycle will keep repeating.

89
Moisture in theRefrigerant Circuitcontinued
12.6.1

• Moisture in the system will cause the unit to
  malfunction. Moisture will form ice in the
  refrigerant control at the point the liquid
  refrigerant is expanding into the evaporator.
  This is noted by the following.
• Warming the refrigerant control using a safe
  resistance heater (hot pad) or radiant heat bulb
  during system shutdown will cause the ice to
  melt. If the system begins to work properly,
  moisture is present.
• Moisture creates corrosion problems within the
  system. The refrigerants react with the water
  molecules to form acids. The acids increase
  corrosion.

90
Moisture in theRefrigerant Circuitcontinued
12.6.1

• Moisture in the refrigerant circuit may be
  removed by installing a drier in the liquid line.
  The procedure is
• Install gauge manifold.
• Recover refrigerant.
• Dry and clean filter-drier connections.
• Apply flux.
• Heat the connections.
• Remove the old drier.
• Install the new drier.

91
Moisture in theRefrigerant Circuitcontinued
12.6.1

• Procedure (continued)
• Braze the connections.
• Test for leaks.
• Evacuate the system.
• Charge the system.
• Warm the refrigerant control enough to melt the
  ice. The drier will absorb the moisture as it
  circulates.

92
Wax in Oil
12.6.1

• A small amount of wax is contained in oil.
• Oil circulates with refrigerant. Sudden expansion
  at the refrigerant control, accompanied by low
  temperature and pressure, cause some wax to
  separate from the oil. This wax collects in the
  refrigerant control. Over time, it may restrict
  flow or clog the control.

93
Wax in Oilcontinued
12.6.1

• A restriction can be checked with a piercing
  valve. Observe the following
• A pressure test showing low-side pressure to be
  very low.
• Liquid refrigerant shows up in the condenser.
• The unit does not produce any refrigeration at
  all.
• Always clean or replace a clogged valve or
  capillary tube. Pack the control in dry ice prior
  to removal to keep ice or wax locked in the
  faulty refrigerant control.

94
Shortage of Refrigerant
12.6.1

• Shortage of refrigerant usually indicates a leak
  in the system. Lack of refrigerant is indicated
  by
• Low-side pressure below normal.
• Evaporator (or the outlet end of the evaporator)
  that is warm.
• High-side pressure that is below normal.
• Piercing valve mounted on the outlet of condenser
  that, when opened, allows only gas to escape.

95
Gauge (Service) Manifold Types and Construction
12.7

• A gauge (service) manifold is used to service a
  hermetic system.
• Two types of manifolds
• Block manifold.
• Standard manifold.
• Gauge manifold with two gauges, two hand valves,
  and three separate lengths of flexible
  refrigerant tubing is most useful for performing
  necessary operations.

96
Gauge (Service) Manifold Types and
Constructioncontinued
12.7
97
Gauge (Service) Manifold Types and
Constructioncontinued
12.7

• The hoses have 1/4" (6mm) flare fittings with
  synthetic rubber gaskets. Connections can be made
  pressure-tight with finger pressure alone.
• Manifold gauges can be used to produce a vacuum.

98
Gauge (Service) Manifold Types and
Constructioncontinued
12.7
Usage of a Gauge Manifold for Various Purposes
99
Connecting a Gauge Manifold
12.7.1

• Gauges are used to check pressure in a system.
• Connection must be made without air, moisture, or
  dirt entering system.
• System design determines procedure for connecting
  gauges.
• Purge hoses prior to and following service.
• When checking high-side pressure, use piercing
  valve if system is already charged.
• If system is not charged, braze a process tube
  into the condenser line.

100
Connecting a Gauge Manifoldcontinued
12.7.1

• After installing gauge manifold, operate system
  through at least three cycles.
• Record suction pressures, condensing pressures,
  evaporator temperature, and the condenser
  temperature.

101
System with Two Service Valves
12.7.1

• Easiest for attaching gauges.
• Permits checking both the low-side and high-side
  pressures.
• Most common on commercial systems.

102
Valve Adaptor
12.7.1

• Used with hermetic systems.
• Adaptor is fastened to the dome.
• Adaptor has removable service valve.

103
Process Tube
12.7.1

• Can be adapted for service by installing a
  piercing valve.
• Used to evacuate, test and charge the new unit.
• May braze an extension to it.

104
Piercing Valve
12.7.1

• Most common method of accessing a small hermetic
  system.
• Mounted on the suction tubing, discharge tubing,
  or both.
• May be mounted on a process tube.

105
Purging Service Lines
12.7.1
106
Hermetic ServiceValves and Adaptors
12.8

• Most hermetic refrigerators do not have service
  valves.
• Some have fittings to which valves can be
  attached.

107
Hermetic ServiceValves and Adaptorscontinued
12.8

• Purpose for attaching service valves
• Check internal pressures.
• Discharge system or add refrigerant.
• Add oil.
• Evacuate the system.
• Make it easier to replace driers, motor
  compressors, evaporators, and refrigerant
  controls.
• Recharge the system.

108
Hermetic ServiceValves and Adaptorscontinued
12.8

• Use of a service valve adaptor
• Connect a flexible charging line to the service
  valve adaptor.
• This is attached to either a hand valve or a
  service manifold mounted on the other end of this
  tubing.
• The valve should be loose at the attachment
  point.
• Use vapor from the cylinder to purge the lines.
• Gauge may be located on the compressor dome,
  suction line, or process tube.

109
Hermetic ServiceValves and Adaptorscontinued
12.8
110
Systems with Valve Adaptors
12.8.1
Valve adaptor is fastened to the compressor dome.
111
Systems with Valve Adaptorscontinued
12.8.1
Adaptor has a removable service valve.
112
Systems with Valve Adaptorscontinued
12.8.1
Valve and adaptor connect together.
113
Systems with Valve Adaptorscontinued
12.8.1

• Service valves may have two openings.
• One for pressure gauge.
• One for performing service.

114
Systems with Valve Adaptorscontinued
12.8.1

• Procedure for using valve adaptors
• Clean outside.
• Remove dust cap from adaptor.
• Choose correct valve stem drive.
• Push the service valve stem forward in body of
  valve attachment.
• Engage the valve stem in the valve adaptor
  needle.
• Thread the valve adaptor unit into the attachment
  body.
• Use good gaskets.

115
Systems with Valve Adaptorscontinued
12.8.1

• Procedure for using valve adaptors (continued)
• Prior to opening valve adaptor needle, tighten
  packing unit around the valve stem.
• Bleed the passages.
• Purge the assembly.
• Leave flexible line fitting loose at valve
  attachment.
• After purging, tighten the loose connection.
• Always test for leaks using a refrigerant
  pressure of 15 psig (30 psia) to 20 psig (35
  psia) (206.8 kPa to 241.3 kPa).

116
Process Tube and Adaptors
12.8.2

• As handle is turned, ball bearing presses into
  the tubing, compressing it.
• Process tube can be used for service by
  installing a piercing valve on the process tube.
• An extension may be brazed to the process tube or
  a process tube adaptor mounted on it. Adaptors
  are of various sizes.

117
Process Tube and Adaptorscontinued
12.8.2

• Pinch-Off Tool.
• Used when necessary to seal off soft copper
  tubing (up to 3/8" OD).
• Has screw-type action shaft with a ball bearing
  on the end that presses against the tube.
• Tool is placed over the copper tubing.ABefore
  pinch.BAfter pinch.

118
Process Tube and Adaptorscontinued
12.8.2

• Pinch-Off Tool (continued).
• Produces a permanently pinched line.
• Tool is left in place until adaptor is removed.
  Brazing seals tubing end.
• Can be used in an emergency to isolate parts.
• ADone with pliers-type tool.BDone with tool
  shown on previous slide.

119
Piercing Valves
12.8.3

• Most common method for accessing small hermetic
  systems.
• May be mounted on suction tubing, discharge
  tubing, or both.
• May be mounted on process tube.

120
Piercing Valvescontinued
12.8.3
Two general typesABolted-on.BBrazed-on.
121
Installation ofBolted-on Piercing Valves
12.8.3

• Tubing must be straight, round, and clean.
• Be certain there is enough space to operate the
  valve.
• Place a small amount of clean refrigerant oil on
  the tubing.
• Check that the synthetic sealing washer is in
  place and needlepoint piercing valve stem is all
  the way out.
• Mount the valve on the tubing.
• Tighten the unit clamping screws evenly.
• The valves are usually left in place on the
  system.

122
Installation ofBolted-on Piercing
Valvescontinued
12.8.3
Three types of piercing valves.ACharge-and-tap
valve.BHand-valve type.CLine-tap type with
hexagonal wrench.
123
Installation ofBrazed-on Piercing Valves
12.8.3

• Safe to use since neither the suction tubing nor
  condenser tubing has liquid in them. However,
  make certain no flammables or soft-soldered
  joints are near the brazing area.
• Be certain tubing is straight and round at
  brazing point.
• Clean the saddle and tubing mating surfaces with
  clean sandpaper or steel wool.

124
Installation ofBrazed-on Piercing Valves
continued
12.8.3

• Remove the piercing valve stem and the gasket
  from the saddle.
• Put clean, fresh brazing flux on the saddle.
• Mount saddle on tubing, ensuring clearance for
  mounting the valve.
• Heat both the tubing and saddle until filler rod
  material flows around saddle.
• Do not move or shift saddle during brazing or
  cooling process.

125
Installation ofBrazed-on Piercing Valves
continued
12.8.3

• Caution Do not overheat the tubing. It may be
  weakened to point of failure and burst. Wear
  goggles during the brazing operation.
• Inspect joint and, when cooled, install the
  piercing needle and gasket.
• Unit is now ready for installation of service
  valve attachment.

126
Questions

• Should there be a separate circuit from the
  circuit breaker panel to the refrigerator-freezer
  outlet?

Yes.

• How much space must there be between a
  refrigeration unit and surrounding surfaces if
  the outside shell of a cabinet is the condenser?

At least 2" (50mm).

• Refrigerators with a separate freezer compartment
  door often have an electric heater around the
  door opening. This is referred to as a
  ___________________.

mullion heater
127
Questionscontinued

• In a frost-free or automatic defrost
  refrigerator, what does a formation of frost
  indicate?

Defrost system malfunction.

• What may cause the outside of a refrigerator to
  feel colder than normal?

Insulation within the unit has gotten wet.

• What symptoms are found with dirty or loose
  electrical connections?

High temperatures causing discoloring of the
connection (blue or greenish tint).
128
Questionscontinued

• What is the maximum allowable voltage drop to a
  refrigerator?

10.

• Before servicing a capacitor, what safety
  precaution must be taken?

Short the capacitor using a 20,000W (20kW), 2W
resistor.

• What are symptoms of a defective mullion heater?

The door gasket freezes to the cabinet or
excessive condensation around the door.
129
Questionscontinued

• When testing single-phase motor terminals, which
  two terminals will have the highest resistance?

Between the run and start terminals.

• Name two internal service procedures.

Removal of any hermetic system component and loss
of refrigerant charge.

• Name two problems that will occur if liquid
  refrigerant reaches the compressor.

Broken valve and thinning of refrigerant oil.
130
Questionscontinued

• What symptoms will be found if moisture freezes
  at a refrigerant control?

Low suction pressures (vacuum) until refrigerant
control is warmed. Pressures then return to
normal.

• What other problems can moisture cause in a
  refrigeration system?

The formation of hydrofluoric and hydrochloric
acids.

• What can cause wax to separate out of refrigerant
  oils?

Sudden expansion at the refrigerant control,
accompanied by low temperature and pressure.
131
Questionscontinued

• Name two symptoms indicating a lack of
  refrigerant charge.

A decrease in both low-side and high-side
pressures.

• Name three purposes for attaching service valves
  to a hermetically sealed system.

Check internal pressures, add refrigerant, and
add refrigerant oil.

• Name two general types of piercing valves.

Bolted-on and brazed-on types.
132
Core Valve
12.8.4
Many systems use a Schrader core valve to access
a hermetic system.
133
Core Valvecontinued
12.8.4
A clamp-on core valve adaptor is used with
flexible service tubing fitting with a pin. The
pin depresses the core valve stem as the fitting
or service device is mounted.
134
Core Valvecontinued
12.8.4
A service valve attachment that mounts on the
Schrader valve adaptor may be used. Its long stem
loosens the valve core while evacuating the
system. This allows more flow of vapor when
drawing a vacuum.
135
Locating Refrigerant Leaks
12.9

• Although testing for leaks may vary with
  refrigerant used, all methods require applying
  pressure to the system with an inert gas such as
  nitrogen.
• To begin testing, a positive pressure of 5 psig
  (20 psia) to 30 psig (45 psia) (137.9 kPa to
  310.2 kPa) is necessary throughout the circuit.
• If no leaks are found, test again at or above the
  normal condensing pressure for the refrigerant.
• Check for leaks prior to evacuating the unit.
• Use proper recycle/recover equipment.

136
Locating Refrigerant Leakscontinued
12.9

• An electronic leak detector can be used for leaks
  of CFC, HCFC, and HFC refrigerants.
• If a leak is found and service has occurred,
  recheck the complete unit for additional leaks.

137
Pressure-Testing for Leaks
12.9.1

• With proper care, nitrogen may be used when
  testing for leaks.
• Pressure in the nitrogen cylinder is about 2000
  psig (14 Mpa).
• Caution A pressure-reducing device that has both
  a pressure regulator and a pressure relief valve
  must always be used when testing with nitrogen.

138
Pressure-Testing for Leaks
12.9.1
139
Pressure-Testing for Leakscontinued
12.9.1

• Caution A refrigerating system can explode if
  pressure is allowed to build up in the system.
  Too much pressure can lead to serious/deadly
  accidents.
• Prior to using nitrogen to test a system, check
  the system nameplate. In most cases, it will give
  recommended testing pressures.
• Caution If pressures are not known, never test
  all or part of a hermetic system at a pressure
  over 170 psig (185 psia or 1275 kPa).

140
Pressure-Testing for Leakscontinued
12.9.1

• Caution Never use oxygen or acetylene to develop
  pressure when checking for leaks. Oxygen will
  cause an explosion in the presence of oil.
  Acetylene will decompose and explode if it is
  pressurized over 30 psig (45 psia or 310.2 kPa).

141
Leak Detecting Devices
12.9.2

• System leaks are usually very small, so sensitive
  detecting devices are needed.
• Commonly used devices
• Bubble solutions.
• Fluorescent dyes.
• Refrigerant dyes.
• Halide torch.
• Electronic detection.

142
Bubble Solutions
12.9.2

• A water-soap solution is brushed over an area
  suspected of leaking.
• Gas coming through the solution will cause
  bubbles.
• Advantages include ease of use, low cost, and
  ease of application, and use around urethane
  insulation.
• A disadvantage is that the larger leaks will blow
  through the solution and no bubbles will occur.

143
Refrigerant Dye andFluorescent Leak Detecting
12.9.2

• Dye in a system produces a bright red color at
  the point of leakage.
• Most leaks show up quickly however, up to 24
  hours may be required in some cases.
• In most systems, the entire refrigerant charge
  must be replaced with refrigerant containing the
  dye.
• An ultraviolet fluorescent leak detector scans
  the system. May be used with a variety of
  refrigerants, including R-134a.

144
Refrigerant Dye andFluorescent Leak Detecting
12.9.2
145
Halide Torch Leak Detector
12.9.2

• Notes presence of halogen refrigerant by
  displaying a light green color.
• Torch burner is at top. One end of rubber tube is
  connected to base of burner. Other end is moved
  to various parts of system. Rubber tube draws air
  from open end into burner.

146
Halide Torch Leak Detectorcontinued
12.9.2

• When open end of tube nears leaking connection,
  it draws up some of the leaking refrigerant
  vapor.
• When vapor contacts the burner, the flame color
  becomes green indicating a leak.

147
Electronic Leak Detector
12.9.2

• Three commonly used types
• Electrochemical sensor.
• Ultrasonic.
• Dielectric.

148
Electrochemical Sensor
12.9.2

• Ceramic layer covered by reactive element
  maintained at high temperature by a built-in
  heating element.
• Contact with halogen-bearing gas causes an
  electrical current to flow to a collection
  electrode.
• No need to reset detector for different
  refrigerants. No need for technician to determine
  refrigerant in use.

149
Dielectric (Electronic) Sensor
12.9.2

• Detects all halogenated refrigerants except R-14.
• Caution Electronic leak detector should not be
  used in areas containing explosive or flammable
  vapors.
• Avoid drafts when using.
• Gases are run between plates of a capacitor.
• Gases act as the dielectric (insulator) for each
  capacitor.

150
Dielectric (Electronic) Sensorcontinued
12.9.2

• Leak-detecting probe is passed below suspected
  leak.
• If leak exists, refrigerant is drawn into probe.
  New vapor changes the resistance in the circuit.
• Detector will emit a piercing sound, or light
  will flash, or both.

151
Ultrasonic Leak Detectors
12.9.2

• Use headphones and a portable, hand-held
  detector.
• Ultrasonic frequencies are sound waves beyond the
  range of human hearing.
• Detect the sound that vapor makes escaping from a
  pressurized system.

152
Repairing Leaks
12.10

• Remove and recover the refrigerant from the part
  of the system with the leak. (Note In some
  cases, you may have to empty the complete
  system.)
• Check the pressure to ensure it is 0 psi (no
  pressure or vacuum in the system).
• Avoid soldering or brazing a system with
  refrigerant in it. Heat may break down the
  refrigerant.

153
Repairing Leakscontinued
12.10

• May use nitrogen cylinder connected to process
  tube when soldering or brazing.
• System is pressurized and checked for leaks.
• When leak is found, area can be brazed.
• Recheck for leaks prior to removing nitrogen
  cylinder.

154
Leaks in Tubing Connections
12.10

• May occur at flared connection if
• Tube flare is not correct.
• Flare nut has not been tightened securely.
• Threads are stripped.
• Evacuate system using proper recycle/recovery
  equipment.
• On recovery, use a traditional vacuum pump to
  fully evacuate the system prior to recharging.

155
Leaks in Tubing Connectionscontinued
12.10

• Replace leaking fitting by making a new flare.
• Use a new flared fitting.
• If brazed or silver-soldered connection, repair
  by cleaning, coating with flux, and reheating.
• When reheating, use a fire-resistant material to
  protect nearby materials.

156
Leaks in Tubing Connectionscontinued
12.10

• Caution Avoid overheating other parts of the
  system. Never heat a drier. Moisture will be
  driven out into the system.

157
Refrigerant Recovery and Evacuation
12.11

• Indications of insufficient refrigerant charge in
  a hermetic unit
• Partially frosted evaporator.
• Low-head pressure.
• Low pressure on the low side.
• Unit runs too frequently.
• Confirmation of a leak.

158
Refrigerant Recovery and Evacuationcontinued
12.11

• Procedure for adding refrigerant
• Evacuate the system.
• Connect a refrigerant cylinder to the charging
  manifold. Charge with the correct refrigerant
  vapor.
• Refrigerant cylinder may be heated with warm
  water or electric heater insert.
• Caution Temperature must not exceed 120º F
  (48.9º C). Never use an open flame for heating.

159
Compressor-Running Test 1
12.11

• Start the unit.
• Open the line service valve, gauge manifold
  valve, and refrigerant cylinder valve.
• Observe low-side pressure gauge. Pressure of not
  more than 25 psig (40 psia or 275.8 kPa) should
  be created. Control pressure by adjusting
  refrigerant cylinder valve.

160
Compressor-Running Test 1
12.11
161
Compressor-Running Test 1continued
12.11

• Allow refrigerant charge to enter system for
  three to five minutes.
• Close gauge manifold valve.
• Allow unit to operate and check frost line on
  evaporator.
• If frost line is inadequate, repeat the charging
  for short intervals. Frost line must not go
  beyond the accumulator in the suction line.
• When proper amount of frost is observed, close
  refrigerant cylinder valve, adaptor valve, and
  gauge manifold valve.

162
Compressor-Running Test 1continued
12.11

• Check for leaks using a leak detector.
• If system contained a process tube, pinch off
  with a proper tool. Remove adaptor valve. Flatten
  tube end by crimping and braze end of tubing.

163
Compressor-Running Test 2
12.11

• Mount charging device between the refrigerant
  cylinder and the low side.
• The charging device will allow liquid refrigerant
  to flow into it from the cylinder. The
  refrigerant vaporizes inside the device.
• NoteAlways charge a unit with vapor. Never
  charge liquid refrigerant into the low side of a
  domestic or small commercial unit!

164
Compressor-Running Test 2continued
12.11

• When charging device is first used, process tube
  will sweat and perhaps frost. As unit becomes
  fully charged, sweating and frost will disappear.
• Check suction line temperature. It should be
  about 20ºF higher at 6" to 10" from the
  compressor than at the evaporator outlet.
• If temperature is lower, liquid refrigerant may
  enter compressor and cause damage. If temperature
  is higher, motor compressor may overheat and burn
  out.

165
Evacuation Data
12.11

• A charging device mounted between refrigerant
  cylinder and low side should contain a check
  valve that can be attached to the line allowing
  easy evacuation of system.
• These charging units are available in three
  capacities
• Less than 1 hp.
• 1 hp to 4.75 hp.
• 5 hp to 10 hp.
• The correct size must be used.

166
Compressor-Running Test 3
12.11

• Must have an exact refrigerant charge.
• If overcharged, evaporator will be flooded.
• Use of accumulator at outlet of evaporator
  relieves the problem somewhat.
• Carefully monitor the amount charged into these
  systems.
• Slowly charge system with refrigerant in vapor
  state until suction line starts to sweat or frost
  back. Purge a bit until the frost back
  disappears.

167
Charging with Exact Amount
12.11

• Completely discharge the system.
• Recharge with a cylinder containing the exact
  amount of refrigerant needed as determined by the
  manufacturers recommendations.

168
Reminders Regarding Charging
12.11

• Charge a system into the low side, if possible.
• Refrigerant should be put into the system in
  vapor form. Forcing liquid refrigerant into
  system may damage the compressor and injure the
  technician.
• If a system is short of refrigerant, there is a
  leak. Locate and correct the leak before the
  system is charged.
• Use the proper recovery/recycling equipment when
  locating and repairing leaks.
• If after adding refrigerant to a system it
  becomes noisy, oil should be added.

169
Charging with Portable Charging Cylinder or
Digital Scale
12.11.1

• Charging cylinder with a glass-tube liquid level
  indicator allows transfer of refrigerant into a
  system and measures the amount on a scale. Some
  may be electrically heated to speed up
  evaporation and maintain pressure in the
  cylinder.
• Caution When heating a cylinder or compressor,
  required temperature and pressure safety controls
  must be provided. A pressure control relief valve
  and a thermostat must be provided!

170
Charging with Portable Charging Cylinder or
Digital Scale
12.11.1
171
Charging with Portable Charging Cylinder or
Digital Scalecontinued
12.11.1

• The system has a pressure gauge and a hand valve
  on the bottom. They are used for filling the
  charging cylinder or charging liquid refrigerant
  into a system.
• The valve at the top of the cylinder is used for
  charging refrigerant vapor into the system (the
  best and safest method).

172
Procedures for Use of a Portable Charging
Cylinder after Evacuation
12.11.1

• Attach line from charging cylinder to the center
  of the gauge manifold. Purge with the fitting
  loose at the center part of the gauge manifold.
  Tighten this connection.
• Open piercing valve or valve adaptor and gauge
  manifold valve.

173
Procedures for Use of a Portable Charging
Cylinder after Ev