I have a heat pump outside and a blower in the attic. Both made by YORK. My system stopped cooling a week ago. The blower keeps running but the heat pump does not start.

I checked the circuit breaker in the basement and the power disconnect next to the outdoor unit. Both are good.

I studied the manual it says on cooling calls, the system makes a R to O to reverse the heat pump, a R to Y to energize the contacts which starts compressor and fan, a R to G to start the blower. I removed the cover from the control panel of the heat pump. There were no visible loose wires. I tried a power detector like a screw driver and it detected power on incoming contacts. I watched when the blower started, a small metal plate on the contacts block closed. Then there was a noise that lasted about a second. Both the compressor and fan did not start. The noise repeated about every minutes.

Currently I have the system in "OFF".

What should I do from here?

Thanks, RB

You have power coming into the contacts, but will the contacts pull in? If not and I'd asmune they aren't, with unit on and thermostat calling for cool do you have 24 volts on the coil side of contact. That will be where a small wire will connect on each side. If you carefully pust in on contacts and the unit will run, more than likely the coil is bad and will need to replace complete contactor. Look for a broken wire from air handler to the outside unit. It will be 2 thermostat wires in a brown sheave.

Check the capacitor.

Agree with NorthernHeat the new duel capacitors are one of the biggest problems going, look at the capacitor and see if the top is ballooned where the wires attach, sure sign that it is bad, but they can also be bad with out this . If the capacitor goes bad some times nothing will work even though you have power, Good luck. Mike