Frustration with my roof air

[timjet]

This has been going on for 2 years now and it's time to fix it.
My aft roof top Domenic AC keeps tripping the circuit breaker. The breaker is working correctly as I've seen the amps go up to 80 just before the breaker does it's job of breaking the circuit.
There is no consistency on this fault other than it never happens on start up. The unit will sometimes run for 24 hrs before the breaker trips and sometimes 15 minutes. It does seem to be happening more often.

I've replaced all 3 capacitors, no help.
I've also noticed it never happens during the heat cycle, only cooling.

Suggestions?

[Finance]

Perhaps a fault in the valve that switches from heat to cool? Sounds like locked rotor amps, meaning the compressor is seized. Considering it never happens in heat mode indicates the compressor itself is not the problem... But if the valve sticks halfway or something blocks the compressor discharge then it can’t pump.

I’m not intimately familiar with the particulars of Dometics design, but if it were a residential heat pump that’s what I’d be checking.

[Dom]

Does it trip when its hot out? you could check to make sure your condenser is not blocked with dirt or even lint from trees

[gpounder]

It could be a bad breaker. I would also check to see if you get the right voltage to the unit, Low voltage can cause it to draw more current.

[timjet]

Thanks guys, I know it's not the breaker, I can see the amps spike when it happens. Beside I changed the breaker 2 years ago.
Voltage to the unit is good. This has happened for over 2 years at perhaps 100 camp sites. It also happens at home (I have a 50 amp hookup) where I know voltage is good.



Finance, you mentioned the valve that switches from heat to cool, could you expand on that a little. What would it look like and where would I start to look. Is it replaceable without loosing the Freon charge.


Since the unit works after I reset the CB can I assume the compressor is OK and not frozen?
And expanding on this a little, I've notice when the CB trips, I can reset it, say within a minute and the unit starts up and works normally until perhaps 15 minutes or 24 hours later it trips again.


I have removed the cover and there are no leaves blocking the condenser.

[gpounder]

It sounds like you have done everything you can do, time to replace it.

[timjet]

Originally Posted by gpounder

It sounds like you have done everything you can do, time to replace it.

I don't want to replace it if it can be fixed without a high cost. New AC's at least from what I've heard are not built to the same standards as my 12 yo one is.

[Dom]

Do you know of your reversing valve coil is energized or de energized on cooling? You can tell by placing a small screwdriver across the top of it and it should pull the screwdriver like a magnet if energized. If it is energized, its possible coil is failing causing valve to bounce. I have never seen this senario but it is theoretically possible

[Dom]

Also post a picture of you capacitors. Some older units used a potential relay for the start mode. They can do what you are saying, if they have low voltage

[THenne1713]

Agree on possible dirty condenser and erratic nature maybe the weather influence, but any chance of short-cycling? It too could be an influence?

[timjet]

Originally Posted by Dom

Also post a picture of you capacitors. Some older units used a potential relay for the start mode. They can do what you are saying, if they have low voltage

Here's a picture of the capacitors. I have been told that the little black thing on top of one of the capacitors maybe a problem.

[hypoxia]

Originally Posted by timjet

Here's a picture of the capacitors. I have been told that the little black thing on top of one of the capacitors maybe a problem.

The black thing is a PTCR http://www.tiffinrvnetwork.com/crusingator/P/P-090.pdf Smell it, they usually smell burnt when they go bad. I replaced all of my campers PTCR's with a Supco SPP6, just a personal preference https://www.supco.com/web/supco_live/products/SPP6.html. As a side note, if your residential refrigerator quits, the first thing to suspect is the PTCR, I have spares for every reefer I own as they usually go bad at 5PM Friday.

Are you able to isolate by putting a clamp amp meter on the compressor and the fan? My neighbor had a problem last week, his fan would work for 20 minutes just fine when suddenly the fan motor amps would spike and the fan would quit. You could run the fan without the A/C running to eliminate that.

[Mudfrog]

Everyone has assumed that this is a heat pump we're trying to troubleshoot. OP, just to verify, is this correct?

Not positive this covers the OP's model but it could be helpful:
http://bryantrv.com/docs2/docs/acservice.pdf

[timjet]

This amp spike happens inconsistently. I don't think it is the fan because the AC has never tripped the breaker in heat mode.

And I don't really think it's the PTCR. It looks new and there is no smell to it. I could put an amp meter on the compressor, but I would have to monitor it on the roof for an hour or perhaps 10 days before it would trip the breaker you just can't predict when it's going to happen.


Short cycling was mentioned above. I don't know what that is but I can say as mentioned before, the unit may run 10 days or 1 hour before it trips the breaker. It never trips the breaker on start up. Even if I reset the breaker right after it trips, again it may run an hour or 10 days.