In late July I was on a road trip down the WA and OR coast and experienced a noticeable squawking and squealing sound from the accessory drive area. The event was discussed here: http://www.irv2.com/forums/f22/squea...wa-403100.html
After I got back and investigated further, I started a general discussion about the cause (the clutch dragging having no air-cap between the plate and the pulley surfaces). That discussion was here: http://www.irv2.com/forums/f22/let-s...on-405976.html
During that time I investigated a number of options, and noticed that while lots of compatible part numbers are out there, many come with a variety of pulley sizes, and if you cannot pre-determine the pulley before ordering, you may not be happy with the result. In the discussion thread talking about ac operation, CJ7365 suggested this unit from Amazon: https://www.amazon.com/Delphi-CS0120...ECEEZWCGGDAQG7
My conclusion was because a clutch/pulley assembly from NAPA was about $150, and the entire thing was only $40 more, I'd just replace the compressor. Since the system was working and no internal failures, I passed on buying a receiver and replacing other bits.
While the Amazon site didn't describe the pulley in enough detail, I was able to verify that it came with a 6-groove, 5" pulley by referencing that CS0120 item number and checking different sources and sites. Splendid. I ordered the compressor on 8/12, and it arrived the next day. It took me about a week to get around to doing the install. This thread picks up from the others.
For background, all the special tools you may need to pull or set clutch gaps, gauges for charging, and vacuum pumps for evacuating are available for free from O'Reilly's or Autozone, and I think Advance Auto and probably other places. They charge your card in case you never bring it back, but if you do return the items, then they run the credit. No purchase necessary. This, combined with my old one having virtually as many hours on it as the whole motorhome (we run it pretty much full time when driving) was key in my decision to just replace the whole thing and not just swap the clutch.
As noted in the other threads, compressor work in a chassis like the W-22 is about as close to pleasant as it gets. With the coaches AC running and a race on the telly, a drink on the table, off we go. (Fair warning I have NEVER been able to get text in between pictures. It just puts the pictures at the end, so...
The first is a pic of the view of the old unit after removing doghouse:
4 bolts and it's in your hand, still connected.
I used a piece of plywood as a work surface over the opening.
Then took off the old clutch just to investigate. Yuck. I also removed the pulley, but not relevant to the replacement, so moving on.
I used the gauges (free loan from O'Reilly's) to bleed off the old 134a (that's right, I said it), and swapped the connections on the compressor. A few points to make -
1) The new compressor comes with new seals for the AC lines. When you swap them over, make sure one of the old seals isn't left hung up on the hose end. In my case, one was, so I had to coax that off to replace with the new ones that came with the compressor.
2) the connection on the front of the compressor is what activates the clutch. Straight up unplug/replug.
3) The connector on the back of the compressor is a high-side cut-out switch. it is a normally closed switch which will break connection if excessive pressure is detected. You can TRY to coax the old one out and swap it. You will get annoyed and the plastic gets brittle. $14 and Amazon = new replacement with new seal and snap ring. See pic. If you fail to swap it, you can jumper the connector from the coach and forego the system safety feature. Your money, but your AC will work and barring no excessive pressure events, probably for a long time. Not all GM systems use this cut out switch, but if you have a workhorse chassis, it likely does. In any case, where ever you source the new compressor, it won't come with that switch/connector, so plan ahead.
Using the free gauge set allows you to buy the little cans and not buy the high-priced ones with built in connectors and stuff. The little copper puncture valve used to adapt the gauges to the can is NOT included. You have to buy that. You are still $ ahead. I used 3 12oz cans. No, I didn't measure the weight, cross-check the temp, verify the phase of the moon, and call up Miss Cleo. I used 3 cans, the pressures against the various charts for the ambient temp were Skookum, and that was that.
The old compressor had only 2oz come out from the low side on a dump and measure. Hmmmm. PAG150 is what I found as to the oil viscosity to use. I dumped out the new compressor and got 4 oz. I decided this isn't the new Mars rover, and I'd live with 4 oz back in the new one. Worst case is I mess up a $190 compressor. I can live with that risk. You may not be so cavalier about this stuff - if so you may fuss over the decision. Had I chosen to replace a variety of components, no doubt I could have gotten a solid feel for the oil balance. I chose not to. So far so good.
Did anything not go as planned? YES! Glad you asked. You see, I knew
that connecting the high side port to the gauges was fraught with risk, but since I was putting in a new compressor I really did want to see both sides. Well now...
Not only is the high side port tucked up under kind of above the condenser, but they came from the factory with a little rubber "dust cover" over the valve. Mind you this is UNDER the plastic screw off cap, and embedded down inside the valve assembly. I'm just calling it a "cover" Over time, this rubber cover deteriorates and disturbing what is now brittle rubber wannabe it is a chance you take. Any google search will reveal this, with pics, for those curious. You cannot see it unless you can get eyes over the port. Not happening on my W22, and I bet not on yours either. Sure enough when I was all done, there's that 'psssssss..." sound and putting a finger over the port = yep, it got me.
While that was busy bleeding my newly installed 3 cans into the atmosphere (that's right, I said it again) I toodled back to the store to buy 3 more cans. The ensuing convo with the guy who sold me the first 3 cans - I'll skip that.
The solution to this new issue is to unhook the compressor output line from the compressor and the connection to the condenser. It's about an 18" or so section which includes the high side port. Take it into the garage, carefully remove and blow out the little rubber dust cover bits that came apart and are interfering with the valve seating, and reinstall the line. You can also buy and replace the top part of the port containing the valve. I dunno if new ones come with little rubber covers in there. My clean out of the debris was sufficient given no physical damage to the valve itself. It took me maybe about 30 min, but getting to the connection on the condenser side is a PIA, so take your time. I laid a dog bed across the top of the engine, laid down on that, and that left both arms free to work with the hose. Then as above, evacuated again, recharged, 3 cans, yada yada. i was annoyed by now at what essentially doubled the project time, and didn't take any pics of that rubber piece inside the high-side port. I do regret not taking those pics for the group.
I did not buy the thermometer for the vents and temp. My logic was simple. I'm putting in 3 cans. I have a sealed system. If the temp coming out is 40, or if it's 50, then that's what it is. Well, as it turned out we took a Labor Day road trip and oh my, this was working soooo much better than the "working" unit I replaced. Maybe the 13 year old system didn't still have that full-charge, I dunno. Anyway, the temp readout was verified and cross-checked as "dayum, that's nice and cold again!" Good enough for civdiv99.
I cannot think of anything I left out. I mean, the vacuum pump comes with instructions, 134a temperature/pressure charts are out there, and at the end of the day if you are DIYing this, you probably already understand the theory of operation of a system and what you are affecting. Take off old, swap connections, charge.
If not, IRV2 be here.