ok i checked the white and red wires , they do have volts there . i did try to jumper the contact ..no?

Question

no compressor kicking on . this is on my central air unit a couple of y'all were helping me .

Answer 1

The thermostat supplies 16 volts to the coil of the relay for the compressor. Check for voltage at coil. Make sure thermostat is set on cool and to auto. Ok inside where the cooling coils and heater are, there is a transformer that the thermostat wires go to. If you had no 16 volts at the compressor contact check here. If everything checks out to to this point. Turn off breaker and pull cover off side of compressor. you will see three wires, sometimes one of the wires burns off or is loose. The wires are marked S R G S is start, R is run, G is ground. You will find the start wire comes off a capacitor, compressor will not start and run if it's bad. Before you fool with it take a long screwdriver and short across the termanials, make sure breakers or off first. If everything checks out to this point, the compressor is shot

Answer 2

OK. I can't remember if I answered before or not. Since you have voltage on the compressor relay, did you try and push the relay down or energize it? Just be careful because it will have 220V on it. Just push it down for a second, or just bump it as we say. That should be enough to tell if the compressor is starting. If it doesn't, then your compressor is shot, so it's time to replace it.

You can also verify the thermostat is working by having someone inside turn the temp setting up to 80 and wait for 5 to 10 min and then you can go outside and look at the relay while the person inside turns the temp setting down to 55. This should pull in the starter relay and the compressor should run and the fan on the top of the AC unit should also start. Just be careful doing this, it's not worth getting hurt if you're not sure how to do this.