I have a Carrier Puron. The outside unit (fan and compressor) will not power on (I have checked all breakers etc). I know the unit has access to power, because when I press the "button" on the contactor relay and close the circuit, the fan and compressor turn on. The contactor is a Carrier HN51KB024. Here is a picture:


A friend of mine told me that the problem may be with the control board not sending the power to close the circuit on the contactor. The control board is a Carrier CEBD430433-02A, which I guess has been replaced with the HK32EA003. Here is a picture of it:


The board looks easy enough to replace, but I think they are about 120 bucks, so I want to be sure before I replace it. Anyone have any ideas on how to isolate it and see if the board is the problem?
Other information... about two weeks before I had this problem, I did have a low voltage short with this unit that caused the thermostat to lose power. I found a wire in the outside unit that had its plastic coating rubbed off and was wire on metal inside the outside unit. I fixed the wire and the thermostat popped on and the whole unit ran fine for about two weeks until this problem. Could that short have damaged the circuit board too? I would think it if it did it would have cause immediate problems instead of a two week delay. Then again, I know very little about air conditioning. Anyway, it is hot here in Florida, so any suggestions would be greatly appreciated.

 

Welcome to the forums.

You need to check for 24 VAC on the black and yellow wires either at the board or the wire nut connections where it comes in.

You should also 24 VAC between black and orange.

 

Ok, I will check that tomorrow. Thanks!

 

I got 24 VAC from all wires, connections and the board itself. When I reconnected some of the wires, I would hear a clicking noise in the AC unit- not sure what that is. So since I have power flowing at all of my connections, do you have any other ideas?
Thanks for your help.

 

Explain how you checked for power... sounds like you did it wrong.

 

I took a vol-con XL and touched the where the yellow and black wires connected to the contactor. I also unscrewed the wire nuts and touched each wire independently. I took off the plastic connector on the circuit board where black, yellow, pink, red and orange cable connect to and touched each one of the prongs on the circuit board. I basically touched every wire connection that I could see and my meter went off. Just to make sure that the meter was not giving me "false positives", I threw the breaker on the outside wall and touched the gray and black wires coming into the contactor from the breaker and I did not get a beep, so the Vol-Con seems to be working properly. I hope what I said makes sense.

 

Your non contact voltage tester is not the proper way to check for voltage.

 

Is it the thermostat or the air handler that sends the signal that energizes the winding and pulls down the metal on the contactor?

 

How should I be testing for voltage?

 

With a volt meter that measures voltage.....

 

Oh sorry, I think I did not identify my tester properly. It is a Voltage/Continuity tester, the voltage lights light up (and give the beep) when I tested.

 

OK, I have figured out that the electrical signal is getting to the outside unit to power on. I disconnected the Orange/Black Black/Blue wires that connect the low voltage wire to the circuit board via the wire nuts. I turned on the air conditioner via the thermostat and then went outside and "very carefully" touched the above wires to each other. I hear a "click" from inside the unit and that is it. So something is trying to turn on, and not making it past the whatever piece is clicking. Any ideas?

 

Call a professional... you are not using proper methods/tools for checking voltages

 

I am sorry, what about this part tool Vol-Con XL Tester that I am using do you not like? When I plug it into the a wall outlet, it registers 120 AC. When I use it on the low volatage line both of the low voltage lights light up and it vibrates- per the instructions. So if I am understanding you correctly, you are saying this tool, when it lights up the dual low voltage lights, is really not measuring voltage? Is it just kidding around with me?

 

It is sensing voltage... not measuring it. Just because there is voltage present does not mean it is the correct voltage. I also do not see anywhere in the instructions that it works on 24vac.

 

Unless your meter has a digital readout of the exact voltage then it is not a true volt meter.