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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 OVERLOADS:
- High voltage wiring. Make sure the voltage is correct supplying the compressor. Check this at the CONTACTOR. Never remove the TERMINAL BOX COVER on the compressor to measure this voltage. You should remove the cover to examine the wires and connectors when the voltage is off, though.
- Run capacitor. 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.
- Stuck compressor. Compressor do stick, just like any other motor. Read the material in Compressor will not start but outdoor fan runs
- Refrigerant undercharge. The compressor is totally dependent on the correct amount of refrigerant being in the system. The system has been designed so the refrigerant will do the job of heating of 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
- 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 cream 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 heating effect of the indoor unit will be poor, the life of the equipment will be somewhat shortened and your electric meter will be spinning at a much faster rate.
- Outdoor fan motor bad. Outdoor fan motors will sometimes have a problem and will quit running. The compressor will continue to run until the coils ice badly and the compressor will be flooding with refrigerant and may shut down on internal protection.
- Excessive indoor temperatures during the heating mode. If the temperature is excessive for whatever reason, the compressor will shut down on a thermal protector. If you must start a compressor under such conditions, then expect it to possibly shut down periodically and later come back on line. This is the best it can do.
- Restricted indoor airflow during cooling. The strain on the compressor from a restricted indoor airflow can be disastrous. Restriction of the airflow in the heating mode of the heat pump will cause the high side pressure to be very high and stress the compressor badly causing it to run hot and produce poorly. Check the cleanliness of the indoor coils and the filter.
- Three-way valves, thermostatic expansion valves and check valves can fail in the heating mode and will likely make the compressor overheat and will trip the internal overloads. Sometimes the 3-way valve will hang in a half-way position and will bypass hot gas back into the compressor suction tube. The failure of the 3-way valve, the expansion valve, or the check valve will cause very poor heating and sometimes unusual noises. The high side pressure will be abnormally high and the compressor has no cool gas coming into it to keep it cool. You can easily check the temperatures of the gas flow in the 3-way valve and the expansion valve or check valve. If refrigerant isn't flowing the direction it is supposed to, then replace the part at fault.
- 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.
- 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.
- Run capacitor. If the run capacitor is shorted through or if it is inoperative, the compressor internal overloads will trip
- Contactor points. Make sure the points of the CONTACTOR are in good condition.
- Inefficient compressor. Compressors can become very inefficient pumps -- valve break and bearing get tight. When this happens, sometimes, the compressor will be under stress and will either trip the internal overloads from excess heat or excess current draw. Either way, this is a terminal problem and the unit will have to be replaced.
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