North Trail - AC Stops Working

[Sumo]

My AC works ok for about 6 hrs than stops for no apparent reason.
I have tried turning Off/On the AC breaker, and the main RV breaker. But none of these thing correct the problem. The AC or the AC fan would not work for days, so I don't think it's frozen/iced up.
Started up today and ran for 3 hrs before stopping.
I get a "click" sound when the AC or AC fan is turned on, without starting, but nothing else.
Had it to the local dealer one too many times, they are unable to find the problem.
Is their a re-set button some where on the AC unit.
The AC is a 13.5 Dometic.

 

[danemayer]

Re: ATF: North Trail - AC Stops Working

Hi Sumo,

Sorry you're having this problem and that your dealer has been unable to resolve it. I assume it's not failing when they look at it so they haven't been able to effectively troubleshoot the problem.

As a general rule, the control flow starts with the thermostat, which signals a relay box that it's time to apply power, or cut power to the compressor and fan. Most of the time, when the thermostat signals that it's time to stop, there's a graceful shutdown where the compressor stops first, followed by the fan. Your description sounds like both go off at the same time and both stay off. You also didn't mention any spitting of water or ice that might indicate a freezeup. You also mentioned a click sound when the thermostat calls for cooling, but the unit doesn't actually start.

Given all that, it sounds to me like maybe the relay is failing or has a loose power connection. But even though the symptoms don't sound so much like a thermostat problem, you might want to check for loose wires inside the thermostat first since it's probably the easiest thing to check.

If you're comfortable working with AC and feel you can do so safely, next would be to take a look inside the relay box. It's probably in the ceiling above the main air distribution grill.

To be safe, disconnect from shore power for an initial look.

Remove the grill mounting screws and the cover plate for the relay box. The relay box has connectors and 110V wires going into it. Look for signs of arcing or for loose wires. Don't go into the box with shore power connected unless you're sure you know what you're doing.

A second place to look would be under the shroud on the roof. Again, you'd be looking for signs of arcing, or loose wires. Power disconnected first.

If you see something that looks wrong, even if you can't fix it yourself, you can point it out to the dealer tech as a possible cause.

 

[Sumo]

Re: ATF: North Trail - AC Stops Working

Last time the dealer had my 5th wheel the AC had quit.
I'll use your plan of action and start my own check. I do have an electrical engineer friend who has offered to help. Hopefully it won't to a shocking experience.
Thank you for your help.

 

[zeus7625]

Re: ATF: North Trail - AC Stops Working

Last time the dealer had my 5th wheel the AC had quit.
I'll use your plan of action and start my own check. I do have an electrical engineer friend who has offered to help. Hopefully it won't to a shocking experience.
Thank you for your help.

There's one more place to look before you remove relay boxes and roof panels.
When I was changing out my thermostat in our 21fbs I had trouble getting the unit to work properly. I never got the same reactions from the fan/unit even if wired back. I thought the wires coming out of the wall to the thermostat were solid to the next connection. When I tugged a little too hard to get a little extra slack I got a piece of wire about 4" long in my hand. I fished around and found the other end and then found the twist cap that had come loose.

My point is to make sure the connections from the back of the thermostat are in fact connected to the wire in the wall that goes to the intended equipment. If a twist cap has come loose and a wire is disconnected in the wall, it may be the source of your problem.