Dash AC Problem

Update: JD, I didn't think it could be either. I borrowed a stethoscope to verify it was the compressor. Lo and behold, I found a broken plastic component right at the rear of the compressor. It appears to be some kind of vacuum thingy attached to lines that appear to run back to the transmission. Anyway, i superglued it and the puffing is history! For now, I'm a happy camper.

Washtubman wrote:

I'm not running the compressor, but it makes that puffing sound even when it's not engaged!

Jerry, I really don't know how that can be. That said, I wish there was an expansion device on the parts listing.

j-d wrote:
And Jerry, don't let the compressor run. Just pull that Relay out. You'll still have all your Vent, Heat, and Defrost functions. Where'd you get the Relay? Any auto supply probably has them, but some of the help can't find it unless they get a hit in the computer on Year/Make/Model. You say "Workhorse" and most of the time s/he will respond like a Deer in Headlights.

I got the relay at Auto Zone.
I'm not running the compressor, but it makes that puffing sound even when it's not engaged!

j-d wrote:
Search "compressor" in that linked manual and you'll see where Workhorse provided only the HVAC parts that can be attached to the engine compartment part of the chassis. The rest MAY be GM components from some of their other product lines, or not. I guess that would be in their Delphi product line. A company called SCS/Frigette used to be a big player but I think they're now defunct. Evans TempCon may have taken over part of the slack. It also seems Denso (as in Nippondenso) is involved.
Have you got any product documentation for the "House" part of the coach? You may be able to find a data plate/label on the HVAC Cabinet which should be visible from under the hood, under the front of the coach, or under/behind the dashboard.
I think your original compressor grenaded and caused it to sling the serp belt. I suspect that some compressor fragments may have gotten into the TXV. The Beer Can Drier should have caught some, but I don't know how much of a "filter" they represent. Manufacturers used to care only if pressure got LOW. For the reasons Ernie mentioned, also because LOW pressure will cause the Evaporator Core to freeze over with concentrate that should have stayed as liquid water and dripped out the weep hole in the bottom of the HVAC cabinet. But of late, they don't want high side over-pressure because US Nanny Agency is afraid something'll burst and send refrigerant into the edges of outer space. Where it will further engage those spotted owls capable of high altitude flight. So it may have an LPCO (Low Pressure Cut Off) Switch AND an HPCO (High Pressure) switch as well. If the TXV is blocked or nearly so, Compressor cannot relive its designed High pressure and will develop a lower Low pressure than designed. I wonder if LPCO/HPCO operation would cause Compressor to make odd noises. It should be cutting Off/On during these antics, based on the either of the two Cut Off switches taking power off the coil in that Relay you replaced.
Do you have a detailed, itemized invoice for the Compressor replacement? If you do, please photo and post it, or type out the Parts Provided and Labor Performed portions.

New AC Delco Compressor, new Parker drier, new pressure switch, AC flush.
System recover, evacuate and charge. Flushout AC.

And Jerry, don't let the compressor run. Just pull that Relay out. You'll still have all your Vent, Heat, and Defrost functions. Where'd you get the Relay? Any auto supply probably has them, but some of the help can't find it unless they get a hit in the computer on Year/Make/Model. You say "Workhorse" and most of the time s/he will respond like a Deer in Headlights.

Search "compressor" in that linked manual and you'll see where Workhorse provided only the HVAC parts that can be attached to the engine compartment part of the chassis. The rest MAY be GM components from some of their other product lines, or not. I guess that would be in their Delphi product line. A company called SCS/Frigette used to be a big player but I think they're now defunct. Evans TempCon may have taken over part of the slack. It also seems Denso (as in Nippondenso) is involved.
Have you got any product documentation for the "House" part of the coach? You may be able to find a data plate/label on the HVAC Cabinet which should be visible from under the hood, under the front of the coach, or under/behind the dashboard.
I think your original compressor grenaded and caused it to sling the serp belt. I suspect that some compressor fragments may have gotten into the TXV. The Beer Can Drier should have caught some, but I don't know how much of a "filter" they represent. Manufacturers used to care only if pressure got LOW. For the reasons Ernie mentioned, also because LOW pressure will cause the Evaporator Core to freeze over with concentrate that should have stayed as liquid water and dripped out the weep hole in the bottom of the HVAC cabinet. But of late, they don't want high side over-pressure because US Nanny Agency is afraid something'll burst and send refrigerant into the edges of outer space. Where it will further engage those spotted owls capable of high altitude flight. So it may have an LPCO (Low Pressure Cut Off) Switch AND an HPCO (High Pressure) switch as well. If the TXV is blocked or nearly so, Compressor cannot relive its designed High pressure and will develop a lower Low pressure than designed. I wonder if LPCO/HPCO operation would cause Compressor to make odd noises. It should be cutting Off/On during these antics, based on the either of the two Cut Off switches taking power off the coil in that Relay you replaced.
Do you have a detailed, itemized invoice for the Compressor replacement? If you do, please photo and post it, or type out the Parts Provided and Labor Performed portions.

I appreciate all the input. I've gone as far as I can. So will not use it until I can get it checked out by an expert. By the way, the drier is the smaller black beer can size, so I guess it's not suppose to cycle.
At least I can now turn it off. I'm still concerned by the puffing sound from the compressor.

Washtubman:
I also wanted to add that if,initially, your ac system ran out of refrigerant and, for some reason, the compressor didn't cycle and turn off, the compressor would continue to run without adequate oiling until it blew up. Not sure about my next statement but I believe a lot of the ac units installed in larger rvs like class A s are actually systems from major auto manufacturers like GM. Check with your rv manufacturer as to what system they install.

Washtubman:
I believe that low pressure switch that you disconnected is there to help cycle the compressor when the low side of the system drops down to about <20psi and this also protects the compressor from self destructing when there is no refrigerant flow which is what carries the oil in the system. My advice is that you quit trying to repair this yourself because you're on the road and most likely don't have the necessary tools anyway. Don't get me wrong, you're getting good advice from everyone and seems like you're relatively skilled but consider all the time and money you've already invested and the likelihood of causing further damage to the system of which you've already replaced most of. My gut feeling is that after your compressor blew, the repair shop didn't repair it properly and now you're stuck. The least I would do is not use the ac system until you get back home. Good luck!

The Heating/Ventilation/Air Conditioning (HVAC) unit in your Class A seems to be aftermarket. Your coach builder decides whose HVAC to install. Most aftermarket A/C systems use Thermostatic Expansion Valves (TXV) and do not cycle. Can you trace the compressor discharge line to, then out of, the Condenser Coil(in front of the Radiator)? If the Drier is in a small refrigerant line near the Condenser, it's TXV and shouldn't cycle. Would be black and more or less the size of a beer can. If a cylinder about the size of a coffee can and maybe bare aluminum then system is Cycling Clutch Orifice Tube (CCOT) and will rarely cycle. More likely if weather is cool.
Next task looks like finding documentation on your HVAC. That would be the Cabinet with Heater and A/C Evaporator Cores, Blower, LInes, and Controls. That documentation would include a Wiring Diagram. AND hopefully info on the Refrigerant System, like any safety valves or switches for Low or High Pressure.