[LeviDavid2]

I have an issue with my AC. I turn thermostat to cool and fan in furnace turns on but fan on condensor doesn't. I go out to the condensor and when I manually push in contactor the condensor fan turns on but immediately shuts off when I let go. Any suggestions?

 

[user_12345a]

check for voltage at the contactor.

voltage + contactor not pulling in. disconnect low voltage wires and check resistance of the solenoid

no voltage? check for safeties in the unit (pressure switches), check low voltage circuit.

 

[BayouRunner]

Check float switch in your safety pan

 

[LeviDavid2]

When I check the voltage does the power to the AC need to be off?

 

[user_12345a]

shut power to outdoor unit, turn ac on at t-stat, turn temp all the way down.

control circuit is powered by indoor unit.

 

[roughneck]

You likely don't have a contactor issue. It's likely a problem with the control circuit. Do you have overflow switches?
And it's not a good idea to push the contactor in manually.

 

[LeviDavid2]

What's overflow switches?

 

[roughneck]

For condensate. You'll have to trace your wiring to see where they are wired into, if you have one.
You have a meter as well, right? You might need one. Some of this troubleshooting could involve working with live electricity as well.

 

[LeviDavid2]

Yes I just bought a meter tester

 

[roughneck]

You'll have to use it to determine where your control voltage is dropping out.

 

[LeviDavid2]

I'm not getting 24 V. Is it possible I just hooked up a wire wrong

 

[roughneck]

What wires did you unhook?

 

[LeviDavid2]

I replace the whole contactor in general. Before I replaced it I can hear it clicking on and off.

 

[LeviDavid2]

Here's a pic

 

[user_12345a]

The small yellow and the small burgundy wire get disconnected from the contactor with the power off.

Check the resistance across the contactor terminals and check for 24vac between the small wires with a call for cooling, a/c on inside, power to the outdoor unit off.

If there's no voltage, check the low voltage connections in the furnace or air handler.

Check for voltage where the low voltage cable comes into the condenser as there could be a safety device preventing it from coming on.

You have to work through the low voltage circuit -> the problem could be anywhere.

 

[roughneck]

If the contactor was cycling on and off, that's likely another issue and has nothing to do with the contactor itself. Possibly a pressure switch.

 

[LeviDavid2]

Where do I check for low voltage on the furnace?

 

[user_12345a]

don't know what furnace u have.

there's normally a circuit board in the furnace with low voltage terminals, labelled r, c, y, w, g.c. normally in blower compartment.

the wire from the outdoor unit connects to c and y. tighten the screw terminals.

You could also move the wire connected to Y (not the one from the t-stat, the one leading to the outdoor unit) to R, apply power and see if the outdoor unit comes on - rule out the outdoor unit and wiring.

don't leave it for long, coil would freeze.