[ccjohnson]

Hello from wonderful Gila Bend.  I think people here would gladly vacation in Hades to get some relief from the heat. Temps here have been 115-117 the last 3 days.  Since we have had the coach, +/- 5 years, the rear AC has always on occasion tripped the breaker.  Newell checked &serviced all AC's right after we got the coach.  I had assumed that it was possibly a weak breaker as it only happens when it is very hot. I would keep the breaker box door open to help keep breaker cool. What I have observed here is that it seems to be more dependent on outside temp than anything else.  Over 107-108 degrees it will trip in around 5-10 minutes.  Below 107 it runs continuously with no issues.  All night and throughout the morning until temps start to get over 107.   Both front and mid AC's work flawlessly all the time.  The breaker issue is only occurring with the rear AC and only when outside temps are over 107. Any guru ideas on the cause of this phenomenon?

[encantotom]

you are just a little over an hour from us in wittmann.

it hit 120 here saturday.

if you are out our way, stop by

tom

[RussWhite]

Those are some incredibly high temperatures.
You may need to get some additional data to determine for sure what is going on with the unit.
I would suggest a clamp on ammeter with a max/min function. May as well get one that does DC amps too while you are at it.

I think the first thing I would want to know is if the breaker is just doing its job.
For that, open the AC distribution box and clamp your meter on the wire leaving the breaker in question.
When the temperature are in the range you expect a trip, start the max/min function while the unit is running. This is important as if you set the max/min then start the unit you will get a max on startup current and that won't tell you anything as the breaker will not trip on that very short maximum current.

If the breaker is tripping below its rating, replace it of course. If not it will probably be caused by high compressor draw due to very high head pressure. You could confirm that with the meter on the wire to the compressor/s.

Good luck,


Russ - don't do this if you are not comfortable working near live wires!

[Ozarkguy]

You also may want to check the condenser coils n see if they are dirty.. That could cause high head pressure as well...

[77newell]

To add to what Russ said, compare the amps to the other a/c's to help you understand where the problem is.

[PMCBR]

Roof or basement?

[ccjohnson]

Basement air.

[PMCBR]

For the brief time I have owned my coach I have discovered the most problems with my basement air is design. Mine is a 1997 and the basement units exhaust and intake are under the coach next to each other. If yours is the same I think this is your overheating problem and causes your breaker to overload and trip. Now if you have the units that exhaust or intake thru a vented compartment door then forget what I said.  The coach I have does fine when traveling but when it is parked the units overheat. I have changed the cowling in the bay and leave the bay door open. I am soon to have these doors vented so this will not be a problem. 

[Fulltiming]

Clint has the Dometic 13.5 basement airs rather than the SCS units used in at least 1995 and later coaches. There are two units stacked, one on top of the other, in the front street side bay and a third typically mounted in a bay behind the right front tire. I can't remember if Clint has three or four A/C's but if 4, the fourth unit is located in the center of the bay likely under the steps into the coach. The two in the forward bay are open on three sides. The other(s) are enclosed and do receive intake air and vent under the coach so it is one of those that vent under the coach that appears to be tripping out.

[Fasteddie]

Clint has the Dometic 13.5 basement airs rather than the SCS units used in at least 1995 and later coaches.  There are two units stacked, one on top of the other, in the front street side bay and a third typically mounted in a bay behind the right front tire.  I can't remember if Clint has three or four A/C's but if 4, the fourth unit is located in the center of the bay likely under the steps into the coach.  The two in the forward bay are open on three sides.  The other(s) are enclosed and do receive intake air and vent under the coach so it is one of those that vent under the coach that appears to be tripping out.

I had the same problem with my 86 Newell on one of the 3 basement Dometic  A/C in my coach. I also replaced the breaker, but did not help. We live in Texas and when it got real hot that one breaker would open. I could tell when it triped as one of the Voltmeters on the front panel would be at Zero. Never did solve the problem.