After replacing a blown running capicitor on the outdoor unit I have power to the contactor but the unit won't come on when the thermostat calls for cooling. I can manually engage the contactor and the fan and compressor come on. I had no meter to check the power to the coil so I plan to do that next and assume a bad coil if power is there. If not then I assume either the thermostat or the 24v transformer. Am I missing anything?

Assumption will bite you on the butt every time. Is the blower motor running when you make the thermostat call for cooling or if you turn the fan switch to on ? If so its not the transformer. Make sure you did not knock a low voltage wire loose while replacing the run capacitor. If it's a rheem heat pump reset the high pressure switch.

Yep, sounds like low voltage prob. The broken or loose wire trick can cause a lot of headaches,,

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Originally Posted by T-Top

assumption will bite you on the butt every time. Is the blower motor running when you make the thermostat call for cooling or if you turn the fan switch to on ? If so its not the transformer. make sure you did not knock a low voltage wire loose while replacing the run capacitor. If its a rheem heat pump reset the high pressure switch.

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Yes, the blower motor runs both automatic and manual so transformer is out- thanks. It's an Amana RCC30C2A so I'm not sure about the high pressure switch. I guess it's down to a loose wire or a bad coil then?