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| SYMPTOM |
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| Compressor | Compressor | Compressor | Compressor | Compressor | |
POSSIBLE CAUSE | Starts and | Starts After | Will Not | |||
Will Not Start | Cycles Off | |||||
Runs But | Cycling the | Start. It Hums | ||||
| and Makes No | (Not On | ||||
| Cycles On the | Overload | and Cycles On | |||
| Noise | Overload) | ||||
| Overload | Several Times | the Overload | |||
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COILS/FILTERS DIRTY OR PLUGGED | X |
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AIR OR NONCONDENSABLE GASES | X | X |
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IN SYSTEM |
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SYSTEM REFRIGERANT OVERCHARGED | X |
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| X | |
DISCHARGE LINE RESTRICTED | X | X |
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CAPILLARY TUBE OR STRAINER | X | X |
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| X | |
RESTRICTED OR PLUGGED |
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FAN BLADE OR MOTOR DEFECTIVE | X |
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| X | |
FAN BLADE OR BLOWER WHEEL STUCK | X |
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| X | |
SYSTEM REFRIGERANT UNDERCHARGED | X |
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| X | |
EVAPORATOR AIRFLOW RECIRCULATION |
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| X | |
UNIT OVERSIZED FOR APPLICATION |
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| X | |
COMPRESSOR REQUIRES START ASSIST |
| X | X |
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NO POWER TO UNIT |
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| X |
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LOW VOLTAGE TO UNIT | X | X | X |
| X | |
OVERLOAD PROTECTOR OPEN |
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| X |
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OVERLOAD PROTECTOR INCORRECT | X |
| X | X |
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OR DEFECTIVE |
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CAPACITOR INCORRECT OR DEFECTIVE | X | X | X |
| X | |
THERMOSTAT CONTACTS ARE OPEN |
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| X |
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THERMOSTAT IS SET TOO HIGH OR LOW |
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| X |
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SELECTOR SWITCH IS OPEN |
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| X |
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OR DEFECTIVE |
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WIRING IS INCORRECT OR DEFECTIVE | X |
| X | X | X | |
SYSTEM PRESSURES NOT EQUALIZED |
| X | X |
| X | |
COMPRESSOR MOTOR OR | X | X | X | X | X | |
MECHANISM DEFECTIVE | ||||||
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COMPRESSOR GROUNDED |
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| X |
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FIGURE 29 — BASIC COMPRESSOR TROUBLESHOOTING GUIDE
5.Next, perform a grounded windings test to test the resistance individually of each wire to the shell of the compressor. The paint on the compres- sor can prevent good contact between the probe and the metal. The paint should be removed from a small section of the shell of the compressor to ensure good contact by the meter probe. The volt- ohmmeter should be set to at least the 100X ohm level. The measured resistance between each wire and ground should be infinite or O.L. on the readout. If there is measurable resistance one of the windings is likely shorted to ground. See Figure 31.
6.A compressor that has a winding to winding short or a winding to compressor shell short is electri- cally failed and needs to be replaced. See the Compressor Replacement section for details.
COMPRESSOR REPLACEMENT
Before working on the compressor, read the instruc- tions thoroughly and gather the necessary tools for the job. Review all safety information on unit and in liter- ature. Always turn off all power to unit to avoid the possibility of electrical shock.
Consider the following safety issues before beginning:
•New and unfamiliar tasks should be performed under the supervision of an experienced service technician.
•Personal protective equipment, such as work gloves and safety glasses, should be worn.
•The floor around the work area should be clean and free of debris.
•Make sure tools are the correct tools for the job and that they are working properly and in good condition.
•Never replace a blown fuse without correcting the cause of the original failure. If thermally operated circuit breakers or overloads are tripping, make sure the trip is not due to excessively high tempera- tures or loose connections.
•When brazing suction and discharge lines, cool the lines with a damp, clean cloth to prevent injury.
•Oil may be present in the compressor accumulator and interconnecting tubing. Use caution when removing tubing.
15
