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Ruud heat pump outside unit trips circuit breaker

A) Ruud UPNJ-031JAZ (outside unit) trips circuit breaker (immediately) when put into heat mode.

B) Tstat set to OFF, Fan to auto; circuit breaker reset to on; outside fan & compressor seem to pulse on for one second, then off for thirty seconds, this cycle will repeat indefinitely or until circuit breaker is turned off.

C) Contactor seems to be fine (contacts move freely, holding coil pulls contacts closed when put into heat mode). This contactor has one side constant on (designed to only break circuit on one leg), other side normal spring movement.

D) Start and Run capacitors test OK (my multi-meter has capacitor test mode)

E) Heat strips come on when outside unit trips breaker

Any suggestions?

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Re: Ruud heat pump outside unit trips circuit breaker

Check your wiring between the contactor and compressor for a short to ground, or check the compressor windings for short to ground.
With the Tstat off, the contactor should be open so the only way for the compressor to be trying to do anything is if the 110 volts from the unbroken side are traveling through the compressor to ground. Since 110v is not enough to run it, the overload is kicking it out, cooling off, and repeating the cycle. When you kick on the Tstat, the contactor is supplying voltage directly to ground without going through the resistence of the compressor windings and kicking the breaker.
Post back and let me know what you find.

Posted on Nov 20, 2007

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Hello Jack,

Let me see if I have this right. Your heat pump keeps triping the breaker that is going to your airhandler. The Heatpump is on its on breaker and can not trip the breaker on your air-handler. However, the 40 amp breaker is to you heat pump its self (the outside unit). The thermstat is not the porblem as all it does is call for heat or cool. The problem can be one or a cobination of three things the contactor, the run capcitor or the breaker is weak.

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