A/C electrical?

[QuilavaMan]

My AC unit is a Dometic Duo-therm RV A/C Model No. 57915.532. For the two years that I've had my trailer, it hasn't had a problem, but starting maybe 2-3 months ago, it started to trip its circuit breaker.
The power box routes all power through 3 separate dual breakers, for 6 switches total. The culprit breaker here is the 30/20 breaker, with the 20 amp switch being the AC power, and the 30 amp being the main power switch.
At times, the AC switch trips and shuts it off. However, some times it is the main power switch that trips, which shuts the entire trailer off.
I need to know what the cause is, so that I can avoid the cost of a diagnostic. Bear in mind that I have zero experience with AC systems.

[cwf]

Sounds like a power input is place to begin. What is condition of the plug and cable?

What is your level of Electrical experience?

[wulfraat]

You very very likely have a bad start capacitor on your air conditioner. They go bad it happens.

The start capacitor stores energy and acts as a “shock absorber” when the AC compressor starts so it doesn’t draw / spike with totally crazy currents to the breakers.... They cost about $20 bucks. You can google “how do I replace a capacitor in my RV air conditioner” for videos.

If you are not comfortable getting on the roof and working on the unit and potentially electrocuting yourself messing around with 120v components I’d call a mobile repair service. Will cost you about $150 bucks to fix the problem.

Personally I’ve done it and it’s not a big deal to replace.

[QuilavaMan]

Unfortunately, I have zero electrical experience. And to make matters worse, the panel on the capacitor is faded, so there is no way to really obtain accurate information about it.

[GCinSC2]

Can you find the wiring diagram for your AC? It might be on the unit. There is a chance that the capacitor specs may be on the wiring diagram. A decent multi-meter has a capacitance test function and can give you an actual value. Not hard to check, specs needed to compare readings to specs.

How old is your unit?

Gary

[cwf]

Probably safest to call an RV tech at this point...