A/C trips breaker - in cool weather

[TriumphGuy]

Ok, I am stumped. Our A/C started tripping the breaker 2 years ago intermittently and not often enough for me to start down the road of troubleshooting. Since then I have replaced the motor (because it wasn't completely smooth turning the fan vs our rear A/C unit and it was making some bearing noise). I also replaced the capacitor while I was working on the unit, thinking it had something to do with the breaker tripping.

It still would trip the breaker intermittently, so just before last summer I replaced the breaker itself, thinking it might have gotten worn out. We do run the front unit ALOT, after all.

Well now here I am out for one of our first trips of the season and it tripped again this morning. Here's the thing though - I think I can can say now after looking back at all the other circumstances, that it trips in "cool" weather. Or maybe mild weather, but nothing like a 100+ degree day.

For example, this morning (we're up in the mountains of NC) - we left the MH around 9am when it was in the low 70s outside and still below the set point of 75deg in the MH. When we came back, the rear A/C was on and the front thermostat indicated 77deg (above the set point) - and the front A/C wasn't running. Of course I go back to the panel to look and the breaker had tripped.

In contrast, a few weeks earlier we were camped by the lake just after Memorial Day (in our typical hot and humid southern weather) and no problems at all, even as the temps got in the 90s.

This has been the pattern in the past 2 years, would run fine in hot weather, but when we have mild mornings it will throw the breaker.

It's not a big deal at all to go back and flip a switch and go on with life, but now we've been leaving our (old) dog in the MH instead of taking him on hikes, and I'd rather not worry about it getting to hot here for him (we have the rear A/C going, but still)...

Anyways, after that long intro, would could be causing that? All of my searches turn up threads about A/C tripping the breaker in really hot weather, which is not the problem here.

Thanks!

[TriumphGuy]

STBRetired wrote:
Does the unit ice up in cooler weather?

Good question! will check in the morning, should be cool again.

[TriumphGuy]

2oldman wrote:

enblethen wrote:
Check the neutral for melting or dark coloration on the insulation.

x2 on this.

High amp appliances can burn up connections which present with intermittent problems. At least in my coach they do. Breakers don't always work they way they should.

My air was running poorly and I discovered the hot wire in my 30a plug was burned to a crisp, but touching just enough to run it, sort of.

:S

AGH you guys have a great point. This is why I come here because I know someone will point out what I've missed.

All this monkeying around and I didn't check fundamentals. I have screws loose (ha ha) all around the RV I'm used to tightening, I should have thought about that with the breaker panel.

When we get home I'll check it all out. Will see what I can figure out with the ammeter as well, usually have it in the MH but left it at home...

[wa8yxm]

Things to check
I've found many RVers have a few screws loose.. With shore power OFF and Generator OFF grab a flashlight and a Screwdriver.. Most likely a #2 Square. and tighten every screw in the breaker box/power distribution panel.

One of mine took 3 1/2 turns

Another RVer found a wire-nutted connection likely at the A/C's junction box that needed to be re-done. I'm not a big fan of wire nuts in RV's.

if it runs for a bit THEN trips the branch breaker..

I have the ability to easily monitor overall current (Branch current too if I need to but not as easily)

As the unit runs the idea is to pump refrigerant into the condenser where it sheds heat to the airpassing through and is "Condensed" but if the condenser is all clogged with stuff like Cotton wood Cotton or other **** that's in the air then air does not flow fast enough to cool and heat builds up. pressure builds up The Compressor works harder and as it slows down current goes up (That's a college course to explain) and CLICK goes your breaker.

Most (Other than Coleman) the crud is on the fan side where you can't see it (Coleman sucks air in via the condenser)

There are other possible issues as well.

[STBRetired]

Does the unit ice up in cooler weather?

[time2roll]

I assume the breaker is 20 amps and voltage is 110+ in the RV.
I would break out the clamp-on ammeter and start monitoring the amp draw compared to specification.
Does the breaker trip on start up or while running? High running amp draw is a sign the compressor is failing. Not sure how to explain the cooler weather.

[2oldman]

enblethen wrote:
Check the neutral for melting or dark coloration on the insulation.

x2 on this.

High amp appliances can burn up connections which present with intermittent problems. At least in my coach they do. Breakers don't always work they way they should.

My air was running poorly and I discovered the hot wire in my 30a plug was burned to a crisp, but touching just enough to run it, sort of.

[enblethen]

Have you checked the conductors in the 120 volt distribution panel? Check the neutral for melting or dark coloration on the insulation.