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James A/C Co.
serving Do-It-Yourselfers since 1990.
Satisfying every customer....one at a time!
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Call toll free 1-866-584-0355 or 1-903-759-2160 fax 903-759-4605
309 Patriot Circle, Longview, TX 75604-2240
THINGS TO CHECK IF THE COMPRESSOR CYCLES ON INTERNAL OR EXTERNAL OVERLOADS:
- High voltage wiring. Make sure the correct voltage is being supplied to the compressor. Check this at the CONTACTOR not at the COMPRESSOR TERMINALS.
| Never remove the TERMINAL BOX COVER on the compressor to measure this voltage. Sometimes, under stress and excessive heat, the terminal posts of the compressor will blow out of the compressor and high pressure refrigerant, oil and maybe metal will burst out of the compressor like a 22 rifle shot. You do not want to be in front of it. You should remove the cover to examine the wires and connectors when the voltage is off, though. Even then, don't stand in front of it if you can avoid it. Try to always be one step ahead and two steps aside disaster.
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- Run capacitor.
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Examine the run capacitor or capacitors for bulging, bad terminals or wires and/or for any leakage of fluid from them. Replace them or have them tested by a technician if you suspect them as the cause. If the run capacitor is shorted through or if it is inoperative, the compressor internal overloads will trip quickly after only a very few seconds of running time.
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- Stuck compressor. Compressor do stick, just like any other motor. Read the material in Compressor will not start but outdoor fan runs.
- Start capacitor. If a start capacitor or the relay controlling it become defective, then the compressor will trip the internal overload as it tries to start. If the relay is stuck, then the compressor START WINDINGS will be continually in the circuit through the start capacitor and the compressor internal overloads will trip out. Try temporarily disconnecting the START capacitor from the circuit and see if the compressor will start and run okay. If it does, take the relay and capacitor to a dealer and have him check and/or replace it.
- Outdoor fan motor bad. Outdoor fan motors will sometimes have a problem and will quit running (See If the outdoor fan won't run but the compressor runs, etc) . Remember that the fan may run sometimes and be off others as it heat up and cools back down.
The compressor will continue to run until the pressures become dangerous or the compressor overheats. In either case the compressor internal overloads will shut down the compressor until it cools or the internal by-pass for the refrigerant will open and a loud hissing sound will be heard before the compressor shuts down on internal overloads.
- Internal overloads. The internal overloads could be bad, but this seldom happens unless they have "tripped" many times. If the compressor internal overloads are tripped and the compressor is not overheated, then you may have an overload that will not reset. A heavy jar to the side of the compressor near the top will sometime re-set it. You don't have much to loose at this point, so you might as well try it.
- Refrigerant overcharge. Just as a lack of refrigerant is a problem, so is an overcharge of it. The high side pressure will be excessive and the current draw of the compressor motor will be higher than normal. Liquid refrigerant will dump back into the compressor and try to be compressed by the vanes or pistons and a loud chattering noise can be heard as the compressor strains against the excess. The oil will foam like whipped creme and will wash out of the compressor into the system and the compressor will be running "dry" (liquid refrigerant is an extremely poor lubricant). The cooling effect of the indoor unit will be poor, the life of the equipment will be shortened and your electric meter will be spinning at a much faster rate.
Read the material on Refrigeration Problem or Ice on the Tubing
- Excessive indoor temperatures. If the indoor temperature is excessive for whatever reason, the compressor will sometimes shut down on a thermal protector if has to run very long before the house cools. If you must start a compressor under such conditions (and you will), then expect it to possibly shut down periodically and later come back online. This is the best it can do. You might try setting a sprinkler hose on it for a while and that will help. Be careful not to flood it too much with water, remember the fan is "sucking" a lot of air over and into itself.
- Refrigerant undercharge. The compressor is totally dependant on the correct amount of refrigerant being in the system. The system has been designed so the refrigerant will do the job of cooling the interior of the dwelling and have enough cooling effect left to dump into the compressor and keep the motor and the pump cooled down to a reasonable level. If the refrigerant charge becomes low, then not enough cooling effect is left in the refrigerant when it reaches the compressor to do a good job of cooling it down and the internal thermal controls will shut it down. After the compressor cools, then the control will re-set and the compressor will run again. Make sure the right amount of refrigerant is in the system and that all the other parts of the system are working correctly.
Read the material on Refrigeration Problem or Ice on the Tubing
- Contactor points. Make sure the points of the CONTACTOR are in good condition.
- Inefficient compressor. Compressors can become very inefficient pumps -- valves break and bearings get tight. When this happens, sometimes, the compressor will be under stress and will trip the internal overloads from excess heat. This is a terminal problem and the unit will have to be replaced.
- Restricted indoor airflow. The strain on the compressor from a restricted indoor airflow can be disastrous. The suction pressure will be lower than it should be and the temperature of the suction line will be very cold or frosting. The liquid refrigerant will dump into the compressor and can wash out all the oil and the compressor may lock up or trip out on internal overloads.
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