Dometic rooftop AC trips circuit breaker

I have a Dometic DuoTherm 59516 15K roof top AC..starts just find and blows cold air for about 5 minutes..then the circuit breaker trips...reset breaker, comes on again and same thing..what's the prob? I would think compressor wouldn't come on at all if it was bad.

One of two things probably. Compressor/motor/bearings heating up and dragging or weak circuit breaker. Get a clamp on ammeter and put it on the AC circuit so you can check the amp draw. If it's below the circuit breaker rating when it trips off, replace the breaker..... First check for loose connections at both ends breaker and A/C

Get up on your rig and remove the cover and look at the back side of the condenser coil and see if it's  dirty, you can't tell by the outside it has to be from the inside. If it's dirty the compressor will build up to much head pressure and draw to may amps and trip the breaker just like it's designed to do.

Denny

I think you're maybe right but don't understand...turned it on yesterday and ran for long time but finally tripped the breaker...looked at inside of condenser coils and not dirty on surface...maybe it ran longer because air temp was little lower than before...do you think coils could be dirty enough on interior to cause that?..will get up there and wash with garden hose...is there a cleaner that would help get to it on interior?

If the coils are dirty, the inside is where it will be.

It comes on, but is drawing too much power and eventually trips the breaker (its a slow-blow type).  Either the power draw is at the hairy edge, or the compressor freezes up or the motor bearing overheat, increasing drag and forcing the current draw up til it pops. You need professional a/c help, but they usually replace those a/cs rather than repair them.

I've had a problem similar to this with high amp draw things and a couple of times it was just the lug at the breaker had become loose and over time heated up and caused the breaker to trip.  Just something else to check, I've started checking them anually just to make sure everything stays tight.

Good luck.

Water Dog said:

If the coils are dirty, the inside is where it will be.

Click to expand...

Not on my coach.. And I just cleaned my condenser (Outside) coils, Monday.

I find that it makes a big difference if they are clean or not,  With fresh cleaned coils and GOOD 30 amp service they both run (27 amps measured on the white wire) I've done this twice.. Dirty coils no joy.

To the original poster:

Check your voltage when running, best measurement would be at the A/C but any outlet will do, Mine trip the breakers if the voltage goes down.

The same Campground where I last ran them both on 30 amps has like 5 sites with good power (Coppyer feeders, and big enough) plus about a dozen 50 amps "Premimum" sites, Most of the park has aluminum feeders and if you have 100 volts at the post you are doing better than most, If not for a heavy box hidden in the coach.. I'd not have Air Conditioning at all (Hughes autoformer)

John From Detroit said:

Not on my coach.. And I just cleaned my condenser (Outside) coils, Monday.

Click to expand...

I guess I didn't make it clear enough John, what I meant was the debris normally builds up on the inside surface of the outside (condenser) coils. Which means the cover has to be removed to visually inspect.

AH.. Ok, now I understand.. Full agreement.

yes, I spent Monday on the roof, removed the covers (Both outer and inner) on one of them I had to pull the fan too, cleaned the coils and re-assembled. (The fan needed some serious cleaning and it was easier to do with the thing in my hand instead of where it lives)

called around and found condenser coil cleaner at Home Depot...first thing that I did was check foam filters and switched circuit breakers..be real interesting if this cleaner does the trick.

This is alittle late but here it goes. I purchased 2 Honda 2000 series generators for my 5th wheel. They put out Max 4000watts. In the past month I purchased and replace my 13,500btu Dometic Roof Ac. This was a direct fit and wiring it was a breeze. Maybe 30 minutes in all. Turned on AC and it started cranking out great cold air. The only other thing on was maybe 1 living room light and the TV. What happened after about 2-3hours was the brand new generators were tripping out on overload. The generators were still  running but showed the overload protection had tripped. After replacing the Freeze stat and new control box (circiut board) this was still happening. What I found was when I had the thermostat set for 65 degrees in camper it would trip out the generators. If I set the thermostat to 40 degrees it ran the entire time and never tripped. Of course this is not the correct way to use the AC but it did work and I needed the AC really bad the week of July 18th with the temps we had in NH. When the thermostat was set at 60-65 degrees the air compressor would cycle off when it reached temp. When it called for it to come on is when it would trip. Actually trip 1 generator and a few seconds later would trip the other. I had my electrician and AC speciallist from work reveiw what I found and it was said the amp draw just for the compressor was much more than my generators could produce especially since there is no time delays built into these Honda generators. I dry camp in NH and I havent tried to hook up to a camp site with much more wattage yet. Also, when it gets late at night the outside temp starts to drop I will start to hear the AC make a moaning sound and at that point I shut it off and just run a fan for the remainder of the night. In conclusion I guess I need a larger generator set up for it to work correctly and not cause over voltage.

just got back on this project..had to deal with prostate cancer..everything great
cleaned the coil and turned on..ran for 15 minutes and then tripped the breaker..I think I heard the compressor cycle before it tripped but don't know exactly what was going on when it did..sort of what you were talking about..doesn't make sense if it would run that long and then trip..anyone have any other ideas? don't have an amp meter...could it be too much or too little freon? how do you check pressure since it's sealed?

something else I thought of is put bigger breaker in..it's 20A and don't think 25 or even 30 would cause a problem

Breakers become worn over time allowing them to trip at a much lower amperage. If the circuit is designed for a 20A breaker, do not put in a larger amperage breaker. Most manufacturers build a small safety factor into their products but if you push it to the limits, you are risking overheated wiring and the high risk of fire!  Replace the breaker with what it calls for and see what happens, if it still trips the breaker then you have a problem in the circuit.

Agree with gwcowgill. The wiring to your AC is only rated for 20 amps. Putting in a larger circuit breaker is akin to not having one in the circuit and letting the wire take the heat. A good way to burn down the house.

It sounds as if the breaker is blowing when the AC restarts. This is usually because the head pressure is higher after the unit has run for awhile. If replacing the breaker doesn't help (probably draws about 20-22 A on starting), I'd look to the starter capacitor on the AC, or low voltage.
Ernie

I was out working on my mh today and my air conditioning started doing the same thing (running for about 15 minutes or so then tripping the breaker), only it was tripping the 30 amp main breaker. After a few times of that, and wanting to finish the other project I was working on, I set it on low cool and it lasted for about twice as long. I then removed the dead front on the circuit breaker panel and found that the main neutral wire had burnt half way through and melted the insulation 3/4 of the way back to where it enters the panel.....why? Loose connection at the neutral bar where it was attached. Now I have a project for tomorrow....oh joy...!

Water Dog, any luck on the burnt wire?? i have same issues

PDMokry said:

Water Dog, any luck on the burnt wire?? i have same issues

Click to expand...

This post was from a year ago PDMorky, and yes, it was a simple matter of installing a junction box behind the breaker panel and splicing in a new feed. We have since sold that mh.