Central A/C Control Board?

I have a 6 year old central a/c unit. Over the weekend it started doing some weird thing where the compressor and fan would not run at the same time. (i.e. if the outside compressor kicked in, the fan would stop running). Later that day, the problem turned to where the fan will not run at all, but the compressor will still turn on when the thermostat tells it to. (Just checked it)





I'd like the problem to be a bad cap but I'm not sure b/c before it stopped all together, the fan would run, but then stop 5 minutes later. I don't believe the fan motor is burnt either. So, I'm down to the control board. I have a multimeter and I'm going to check the transformer this morning. Is there anything else I should be looking at when I do that, or is there something I haven't thought of?





Thanks in advance!Central A/C Control Board?
Not quite sure what fan your talking about.


I will guess that it is the fan on the outdoor condenser.


If so some fans are turned off by a head pressure control that shuts off the fan in cooler temps to keep the head pressure up.


It should kick the fan back in as the head pressure rises.


This may be an add on device and would not show up on the original wiring diagram.


I think you should have a tech check this out as a low refrigerant charge may be affecting the normal operation.





Edit:Try running the fan only via the fan switch on the thermostat.


You can then check for voltage to the motor.


Check the temperature of the motor. Motors have an internal overload that will open the circuit through the windings until the motor cools down.


Typically when capacitors are faulty the motor will not turn to start. It would then just sit there energized and eventually heat up enough to trip the overload.