Roof A/C Issue

[joraz]

Class C with a 13.5 Dometic (Model Number: 520316.506E) year 2009


My rig is parked at the house in the hot Arizona sun. The A/C works fine for most of the day but when the ambient temp hits 104 or so the compressor shuts down and the fan blows hot air.

The A/C has had little use over the years. I cleaned both the evaporator and condenser coils although both were already very clean.

The unit is draining as it should and the interior filters are clean.

I did a voltage check over the day yesterday and have eliminated low voltage as the problem.

I have been advised on another forum that the issue could be the overload protector (thermal switch) which is designed to shut down the compressor when it's too hot. So I figured I would just replace it. Problem is that it looks to be internal to the compressor.

Any ideas? Thanks.
jor

Compressor Photos

[joraz]

What is the fan speed?

I have it on high.

Interesting. I just went out to the rig. It's now cloudy but 101 degrees. She's blowin' nice and cold. Who knows!
jor

[Fulltimer50]

What is the fan speed? It should be on all the time on high.

[joraz]

Dometic (year 2009)
Model Number: 520316.506E

I'll take a close look at the capacitors mañana in the morning.
Thanks.
jor

[wa8yxm]

Capacitors do age. and dry out or otherwise fail.

And the compressor may just flat be too hot. And thermal cut out engaging 104 is a bit on the high side for their designs.

one thing that might make it better.. OR WORSE depending on things like mineral content of the water is a "Mister" near the air intake for the condenser. They sell them but the nozzles clog easily (I had 2)

[enblethen]

In the box should be capacitors. Used to start compressor under load and other for run. Inspect the capacitors for any sign of bulging. (swelling)
Make and model of AC unit?

[joraz]

terminal box that was held closed by a spring, and most of those were held against the side of the compressor

That's the thing. Nothing attached to the compressor. Just that barrel-line component which looks like it is pressed into the compressor container. I added a link in my original post to a couple of photos.

[Matt_Colie]

I am dragging up old memories here, so there may be other problems. I replaced a number of over temps that were in the terminal box that was held closed by a spring, and most of those were held against the side of the compressor by a flat spring that dogs into said box.

If yours is like that, you may be able to change out the over temp switch. The trick is going to be getting a replacement. That sure is not a big box or hardware store item. Look for a refrigeration parts place or a Grainger.

Best of luck.

Matt