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Heating, Air Conditioning, Fridge, HVAC/HVAC turns on for a moment and then shuts off


I have a RUUD UAMB-030JAZ condensing unit from 2001. It seemed like it was dead. I checked the capacitor, and while I didn't see any bulges, it looked a little corroded on the outside and maybe like there had been some leakage near one of the terminals. So, I replaced that with a new cap 45/3 MFD 370 VAC. Put the circuit breaker back on and turned on the A/C at the thermostat inside. Came back outside, and it still seemed dead. I opened the circuit breaker, which I hadn't tried before while the unit was supposed to be running, and I heard the relay switch off. I wondered what would happen if I closed the breaker again so I could see what was happening when it was supposedly turning on. I heard the relay close, and for a fraction of a second, the compressor kicked on and the fan blades started spinning up, but then they immediately shut off, and the fan blades glided to a stop (didn't seem like sticky fan blades are the problem). Hadn't tried that with the old cap, so I don't know if this is any change. Does this sound like something familiar? Bad valve? Low refrigerant? Bad compressor? Thanks.

Hi David, it sounds like a bad connection. Pull the disconnect outside by the unit and have someone turn the stat up and down. You should hear the contactor pull in. This will tell you if the stat is ok. I suspect that the disconnect is not making good connection.

Let me know what happens.

Heating, Air Conditioning, Fridge, HVAC

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Jim S.


I can answer questions on gas or electric furnaces, ac units and heat pumps. I don't work on boilers,chillers,or home appliances.


I have been in the HVAC trade for over 35 years. For the past 15 years I have owned my own business. I am semi-retired so I can answer questions in a timely manner.

I attended trade school for 5 years on weekends and evenings. This was very hard to do, but well worth it!

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