GM Workhorse W22 Chassis, 2002 class A coach. Have been having AC issues with a leak that takes several months to evacuate the system. Took it to the shop for the third time; first time was to charge system, second time was to recharge system and add dye, this time was to use a leak detector. They did a leak test and at least found it, it's the evaporator. They only got into it enough to diagnose the issue. Shop said they can't locate a replacement part. Shop owner also said he really doesn't want to deal with it because I can do it myself, it's a big ass vehicle taking up space, it will take days to locate the part, and his tech's always end up breaking something else on the older coaches. I appreciate his honesty, it's the only shop I ever take vehicles to I can't fix myself.
I had them charge the system one more time because I'm taking it on a month-long trip starting Wednesday. When I get to my Arizona property, I'll add a can of Red Devil stop leak and see if that helps. Brother is recently retired senior service writer for GM dealership, and is sure it's a GM part, maybe out of a full-size van. When I get back from the trip I can pull the dash apart, remove the evaporator and get a part number. I'll replace it myself, then have the shop charge the system.
Every "Workhorse" part I have had to replace so far has had a GM part number or been a GM part. The Workhorse labeled parts are two to three times the cost of a GM part. Plugs, wires, coils, ABS sensors, most recently O2 sensors, and even the turn signal multi-switch. GM used that same switch in dozens of models. Workhorse part $149.00, GM aftermarket $24.99. The O2 sensors were Denso. A Workhorse based online vendor wanted $150 each, and when I called them about the part numbers the tech said I could get the same Denso or AC Delco parts off Amazon for much less. He was right, they were $28.00 each. He also gave me the updated version part numbers. Not a very good salesman, but an honest one.
And, it passed smog. I was a little worried because I had a O2 sensor fail on the way back from the last trip and I limped it home from about 100 miles out. Not much choice as no one seems to have parts on hand anymore and I was in the desert. I changed both sensors for updated versions, cleared the codes, drove it around the block and parked it for a month. Not the best scenario for a smog test, but they checked it with a code reader before attempting the smog check and it was clear.