A/C compressor not turning on

Everything works fine except for compressor not turning on. Heat works. But cool only turns on the fan not the compressor.

Is there a 3rd cable not in the picture? I ask because you have a green G wire on the adapter but both cables have a green wire wrapping around the cable. Typically you would see 1 cable going to the condenser carrying C & Y, but in your picture, of the 2 cables, one has C and the other has Y, just seems odd.


The G wire on the adapter is the C wire on the thermostat. The cable with the green wire wrapping around goes to the 3rd picture. The other (bottom) brown cable goes to the compressor outside.
Thanks for helping out!

To test if the pump switch is bad, take it out of the equation.
Connect these wires to each other- if your AC compressor runs, then your pump switch is bad.

How do I do that? Sorry, I have zero knowledge with this…

Connect all 4 together? White red and both blues?

Take the white wire out of the wirenut with the blue wire and put it into the wirenut with the red and blue wire. Don’t worry about the other blue wire for now- this is a temporary diagnostic.

One sec… will try now


Compressor still not on

Do you have any way to check voltage, like a multimeter?

Unfortunately, no.

I could try get one later today

Leave the wire on the pump the way it is. Turn off power to the air handler, so that you don’t accidentally short something out and try taking the white wire that goes to Y and put it in the G slot. Turn power back on. This will test if the compressor is getting the signal to turn on from the thermostat. When it is hooked up like this, the compressor should start running whenever the indoor fan is running. There may be a time delay.

Like this?

And I kept the white and red together from the other picture, right?

Will turn back on now

I can’t post anymore… reached max posts for one day

Compressor still not on. Fan yes

Still can’t reply….

But thanks a lot for the help!!! I will call service. I installed the thermostat in the winter and wasn’t sure if I did something wrong.


Assuming your outdoor disconnect is plugged in correctly, your compressor needs service. Probably a bad contactor or capacitor. Turn the power off and put all the wires back where they were and call your service company.

I upgraded your user level, you should be able to post more now