Question about Carrier 36KCARMS Air Conditioner
I have a trane XE800 1991 not heat pump and I was cleaning the coils and accidently miswired the contactor when I put the fan back. The unit has a brown and a blue or wire that go to the capacitor and a black wire that does to my contactor. I put the black wire on the wrong side of the contractor. What did I fry? Compressor and fan no worky!!!
Check for power at the disconnect and contactor on most residential units you should have 240 volts ac between the terminals
and 120 volts to "ground" or "earth". Some disconnects have fuses in them.
If you have circuit breakers I see little reason for fuses
other than to create a service call. I usually replace them with copper
Most contactors will allow you to push them in manually (DANGER HIGH VOLTAGE). If the fan runs and the compressor does not then you have an electrical problem with the other component. There are cases where a grounded compressor or bad fan motor will cause the fan motor to run slow even though the contactor is not pulled in. A bad run capacitor will cause the compressor not to run and the same for the fan motor. Some units have a dual run capacitor that takes care of both and if it fails (it has an internal fuse) the motors will just hum (drawing high current) but not run. The compressor will have an internal overload that will disconnect the compressor after a few seconds of not starting. It will remake as soon as it cools, this condition can be mistaken as a bad compressor. Some compressor will require a "hard start kit" to solve starting problems and if it doesn't have one I recommend one as a preventative measure.
Use a clamp on ammeter to verify which parts are drawing current. If there is no current flow through the capacitors then that is a clue they may be bad.
DO NOT let your system run if the either fan motor (inside or out) is not working you will destroy your compressor, the same goes if your unit is icing up or short of charge you will burn up your compressor motor.
No control voltage: Most residential units use 24 volts ac to pull in the contactor. The power for this usually comes from a step down transformer in the furnace or indoor unit through the thermostat. Some outdoor equipment will have its own transformer, but this is rare for residential.
If the indoor blower fan wont also work then the problem is NOT the contactor in the outdoor unit but a problem with the thermostat or the wiring to it either at the subbase or the furnace. Before replacing your thermostat you should isolate the cause of the problem or it will persist and drive you nuts. Look for wires touching or cut too long.
A contactor or relay is an electrical device that takes a control signal usually 12 volts DC, 24, 120, 208-230 volts ac and creates a magnetic field to pull in a set of contacts that controls another device that may or may not get its electrical power from the same circuit. Note: 99% of most control circuits are 24 volts AC.
The contactor has steel contacts that are plated with silver. When the silver wears away you have just plain steel and the steel will weld itself together. Sometimes if you whack the contactor with a screw driver you may free it for a while but the problem will re occur. This problem is especially a problem when a piece of equipment has not been run for a period of time.
It is normal for the contactor to wear out over time like brake pads on a car. If the contactor shows any signs of wear it should be replaced as a preventative measure or as part of maintenance.
If you suspect a stuck contactor a 100% accurate test is to turn off the power to the indoor section which removes control voltage to the outdoor section and it (outdoor section) keeps running. Do not keep messing with it, your contactor it is bad and you will destroy your compressor if you let it run!!!
Some heat pump systems use two run capacitors (total of 3 if you include the fan) instead of a crankcase heater for the compressor (GE, Rheem/Ruud and others). It is possible for the contactor to fail where the compressor or the fan will run but not the other. When replacing a contactor on a system like this be extremely careful to get the wiring correct or the compressor may be damaged. so kindly check ur compressor....
both brown and blue wires as mentioned before cary 24volts
If the fan and the compressor dont run then you must have a break in a wire or a bad contactor. It also could be the run capacitor. Either way, leaving the power on could harm the compressor. It may have already. Check to see if the compressor and fan share a run capacitor. It shud be a dual capacitor that boosts the compressor and the fan. It shud read open between the common and each of the other two terminals.
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Posted on Jun 17, 2009
If you cant smell any burning smell and no fumes or smell then disconnect from the mains and put the wires back on,be careful as a capacitor holds electrical charge.Then swap the wire and if you are lucky everything is fine...
Posted on Jun 17, 2009
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Posted on Jan 02, 2017
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