Tripped Circuit Breaker

[jimshoen]

97 Marathon three cruise air set up.
Front (galley) Cruise Air is tripping the (new) circuit breaker in the square D panel after running for 20 minutes. Does this in both heat and cool mode.
Any ideas?

[tdelorme]

Quick shot in the dark. Check to be sure the wires in the Sq. D box are tight. Both the hot at the breaker and the ground
Unplug the coach and turn off the gen. first.

[JIM CHALOUPKA]

97 Marathon three cruise air set up.
Front (galley) Cruise Air is tripping the (new) circuit breaker in the square D panel after running for 20 minutes. Does this in both heat and cool mode.
Any ideas?

Jim, just a shot in the dark. It is possible that the new breaker is defective. If it is cheap and easy try another and see if you get the same results.
If you have clamp-on ammeter take a reading and see how many amps you are drawing.

Probably more than you wanted to know about a clamp-on ammeter in this link:
http://www.allaboutcircuits.com/vol_1/chpt_8/5.html

[truk4u]

Also kill the inverters, they're wired to the A/C.

[garyde]

If the breaker is not tripping on initial start up, but after 20 or so minutes, you may need a new compressor/heat pump or a recharge of coolant.

[Jon Wehrenberg]

Jim,

I think every coach I have ever seen displays the current draw on both the AC and DC circuits.

When you turn the AC unit on there will be a big load when the compressor kicks on, and once it has started the current draw attributable to the AC unit should be around 13 amps. That is the load you should be able to see on your display. You may have other loads, but that will be the expected increase over and above the other loads, and you need to either turn off those loads or at least know what they are and if they are cycling so you can read what is happening with your AC.

A loose wire in the circuit breaker can exhibit the characteristics you describe and so can an internal problem with the AC unit. To make the isolation of the problem fairly simple, rule out the circuit breaker. If the current draw is at or above the rating of the breaker and you have verified the the electrical connections are tight you can focus all your efforts on the AC unit itself. At that point you are no longer using the scattergun approach.

If the current draw is not excessive you likley have a lazy breaker in need of replacement.