Rear Dometic a/c blows 50amp Pedestal breaker

[Jeff753]

Seems when I turn on the rear ac it blows the breaker. Last night it ran for a short time before it tripped the breaker. Front ac ran fine this morning. I asked the cg to check the source ac and have not heard from them yet How do you test the run capacitor and the valve on the ac unit

[GaryKD]

Hi Jeff753,
Are you able to monitor the incoming voltage? If so, it might be good for you to understand if the CG is supplying the proper amount of VAC. I can just about guarantee the CG will always tell you there is nothing wrong on their end. My experience with capacitors is they work or they don't work. With the information provided, I do not think the problem is in your coach.

With summer temps, between 3-8 PM the CG will be on maximum load. Most CGs have a problem supplying the VAC needed.

[1skier]

I would concur with GaryKD - the problem is probably not in your system. If you have a fault in your A/C, odds are that it would trip the closest breaker, meaning in your MH. Could be a flaky pedestal breaker or power fluctuations on the CG line.

[dwhit]

All of us should have a voltmeter available...I carry a FLUKE multimeter with me for myriad reasons.

I also have model 20020 digital monitor that fits in any AC port. Alarm sings loudly at 103vac. Cheap little box checks voltage, phase frequency, polarity and ground.

Cheap reassurance.

[Jeff753]

I have a little cheap plug in digital that shows voltage. I've been looking for something that provides more info. I'll check out yours. Of course I have a volt meter. I'll see what river ridge cg says

[beaverfever]

low voltage = high amps. sound like it may be low voltage. have you tried running it on your generator instead of shore power?

[Redridge]

+1, try the generator. Key is isolation one item at a time. Plug connectors, transfer relay, breaker, AC. A loose connection will essentially draw high amps.

[Jeff753]

Originally Posted by Jeff753

Seems when I turn on the rear ac it blows the breaker. Last night it ran for a short time before it tripped the breaker. Front ac ran fine this morning. I asked the cg to check the source ac and have not heard from them yet How do you test the run capacitor and the valve on the ac unit

Apparently it's how the coach is wired?
See the pics below. If each box represents one leg I have both acs, the fridge and the dryer on the same side.
Cg measured 44 amps on one leg and only 14 on the other.

14 amps on


44 on



Would it be helpful to move an ac to the top of the first panel? Would that matter when I'm on 30 amps?
I plan on looking over the wiring diagram tonight.

[bruceisla]

Have you attempted to run A/C unit #2 (plus miscellaneous as needed) WITHOUT Unit #1? This, most likely, would determine whether unit #2 is O.K.

[bruceisla]

Originally Posted by Jeff753

Apparently it's how the coach is wired?
See the pics below. If each box represents one leg I have both acs, the fridge and the dryer on the same side.
Cg measured 44 amps on one leg and only 14 on the other.

14 amps on
Attachment 41332

44 on

Attachment 41333

Would it be helpful to move an ac to the top of the first panel? Would that matter when I'm on 30 amps?
I plan on looking over the wiring diagram tonight.

I'm a little confused by the labeling .... can you clarify how many boxes you have and what breakers are in each? For instance, the 2 different labels show Inverter L1 and L2.

BTW, I'm assuming you are blowing the PEDESTAL 50 amp breaker and not the RV 50 amp breaker. Since each A/C is on a 20 amp RV breaker, and neither the RV 20 amp breakers nor the RV 50 amp breaker is blowing, this suggests the PEDESTAL 50 amp breaker is weak. Any chance you could move to another site?

However, the 44 amps on one leg is a bit high ... this suggests you wouldn't be able to put that same load on a 30 amp pedestal. Assuming that each A/C is actually using about 13 -14 amps, what is (continuously) using the remaining 16 amps?

[Jeff753]

Originally Posted by bruceisla

I'm a little confused by the labeling .... can you clarify how many boxes you have and what

breakers are in each? For instance, the 2 different labels show Inverter L1 and L2.

Two panels. Each breaker label matches the amperage on the breaker itself. I don't know why l2 inverter is in each of the two panels. I will review the coach wiring diagram (nice 8 1/2 by 17" spiral binder I made and report back.

It seems odd they would put both A/Cs, inverter 1/2, dryer and water heater on one of the legs (panels).

I presume each of the two panels represents a leg of the 50 amp but perhaps the actual wiring diagram will confirm that.

So today they had an amp meter on the pedestal and with two acs and the dryer it was pulling 44 Amps on the one leg and only 14 on the other (ice maker and refer).
There is an empty slot on the less loaded (left) panel I could move one of the ACs too if that would help balance the load

[Old Scout]

Normally the two panels reflect the main distro panel and the second is the distro panel for power being supplied by/thru the inverter circuit. When inverting from your bats, only the items listed on the second panel are powered, eg, not your A/Cs or dryer, hot water heater, or whatever. When on shore power, the main panel supplies 30 amps to your inverter which now by-passes the bats and re-distros the shore power thru/to the inverted curcuits. If your coach is wired for 50 amp, you will have 2-- 50 amp legs supplying your main panel. Usually, heavy users like the ACs and the dryer will be spread across the two 50 amp legs to balance the power--in other words, you actually have 100 amps of power to you coach [across the two legs]. If you are on 30 amps at the pedistal, your 30-50 pigtail feeds the 30 amps across both legs so you only have 30 amps total for your entire coach--a big difference. I am going to "assume" your coach is wired for 50 amps [given that you have two ACs]. Accordingly, the ACs are usually wired on two different legs so if the rear is blowing the breaker, either the rear AC is going bad or you also have the water heater on, the inverter charging bats, the dryer or other things competing for the 50 amps available on that leg. Given if the rear AC runs with nothing else on but blows the breaker when more stuff is added, it may be a weak pole on the pedistal breaker. It may sound complicated but it isnt, really. PM me on this forum and we can discuss this off-line.

PS--ref the 44 amp and 14 amp readings--14 amps is about right for one AC, so everything else in your coach was running on the other leg [44amps]. 44 amps would probably come close to blowing a weak pole on a 50 amp pedistal breaker.

[Jeff753]

I appreciate you sharing your knowledge on the subject. The coach is wired for 50 amps. I am plugged into 50 Amps. The park guys also suspected a weak breaker. Let me research my wiring and I'll pm you. Thanks again!!

[toneumanns]

If you can swap the breakers. See if the problem follows the breakers or stays with the current unit.