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hedwards · 10-10-2022, 09:18 PM

Hi all, I am having problems diagnosing my chassis a/c. The compressor is not engaging, i've demonstrated that the compressor works but no clutch engagement. Just wondering if anyone could give me some pointers, i.e where is the a/c thermostat located, any fused links that i should look for (location)etc. I believe that the pressure switch is near the compressor, if i'm correct it checks out.

TIA for any and all help

My coach is a, 2005 Newmar Mountain Aire on a Spartan chassis

MrMark52 · 10-10-2022, 10:02 PM

Several threads on the site on this - the Search box above will be your friend.

Chances are, your low on charge - but confirm all the electrical details before throwing a set of gauges on it.

Bobby Dowdle · 10-11-2022, 08:39 AM

the a/c dryer should be mounted on the fire wall. That's where you hoses connect. There is a pressure switch with 2 wires on it. Get a fuse and connect the wires to fuse and see if the clutch will engage. If so, it's low on charge.

Jon_C · 10-11-2022, 09:20 AM

I have to charge mine at least once a year or it loses pressure and compressor wont engage. Looked everywhere and cant find leak, I just resigned to adding as needed. Very cold air around 40deg when I put in a few cans and occasionally oil charge.

Ray,IN · 10-12-2022, 09:07 AM

JIC it's needed: Evans-Tempcon all-electric HVAC system service manual for motorhomes.
If that is not the brand of your system; I have manuals for other brands.
This one is not brand-specific: https://www.btrac.com/documents/svc-...i-feb-2011.pdf

Jon_C · 10-12-2022, 10:28 AM

Quote:

Originally Posted by Ray,IN

JIC it's needed: Evans-Tempcon all-electric HVAC system service manual for motorhomes.
If that is not the brand of your system; I have manuals for other brands.
This one is not brand-specific: https://www.btrac.com/documents/svc-...i-feb-2011.pdf

Thanks Ray! Yep mine is Evans and I didn’t have this one.

hedwards · 10-12-2022, 04:59 PM

I found the pressure switch but I can't seem to locate the thermostat, any tips as to where it might be on an 05 Newmar Mountain aire

hedwards · 10-13-2022, 06:37 PM

I found the thermostat and it was fine, however on a second look at the pressure switch it seems to be done? I'll just check a couple of other options and then replace the switch if needed.
Thank you all for your help

MrMark52 · 10-13-2022, 09:18 PM

Which pressure switch did you find? Was it -

High side pressure switch (usually found on drier and is Normally Closed and opens on a rise in pressure.

Low side switch is found in the larger suction return line back to the compressor and is Normally Open held closed by suction pressure.

The low side switch is used to insure the compressor doesn’t run when the refrigerant charge is low which could cause the suction side pressure to fall into a vacuum which allows atmospheric contaminants to enter the the refrigerant system through the leak.

And FWIW -

The thermostat is a contact type of thermostat with a bulb inserted into the evaporator - and is cut-in/cut-out settings are to minimize ice buildup on the evaporator.