Done a search, turned up some useful info, but looking for more.

The backstory: Last month I picked up a 91 RS. Rough around the edges, but runs well. Guy tells me the AC doesn't work. Sure enough, the compressor is locked up... But it's a Sanden, not an R4. There's a receiver/drier attached to the inner fender instead of an accumulator. I stumbled across a C41 non-AC car with some hodge-podge aftermarket AC system installed. I've seen one other car like this a few years ago, looked like the same setup IIRC. I'd like to know if anyone else has run across this, and what all was changed when it was converted? I want to put all the C41 equipment back on it.

I know that the heater box was modified or changed to house the evaporator, the control unit is different (but maybe not the same as a C60 AC control unit?), AC delete pulley is not there, and there's a bunch of shoddy looking wiring and hoses running everywhere.

Pics in the morning if I remember.

 

Some pics of the parts installed.

 

Did a little searching in the little compartment in the trunk and found some useful info. The aftermarket AC is a Wynn's Frostemp system. I found the warranty card for the system, it was installed on the car in January of 92, when the car had 381 miles. Wynn's got out of the AC business in 96 and there's apparently no info or replacement parts out there..

 

Updates:

Recently pulled the evaporator box and replaced it with the proper AC delete heater box. The Frostemp box is a one-piece fiberglass deal. It's definitely not a stock C60 evap box, and it doesn't come out easily until you break it. The wiring for the Frostemp system plugs into the factory connectors, so no wiring got hacked up that I can tell. There was a vacuum operated heater shut-off valve near the heater core inlet with vacuum lines added into the factory blend door lines. A power wire tied into a green wire on the wiper motor with one of those terrible butterfly-spade terminal abominations. Now the under hood stuff looks mostly like it should (except that compressor... fixing that soon). If anyone has pics of an unmodified C41 L03 engine bay they would like to share, feel free to post 'em or PM me.

 

Recently purchased the correct heater control for my car. Pulled it out of the box and compared it to the controls removed from my car. It looks like the factory non-AC controls were modified for the frostemp system, mostly by changing the faceplate and adding the switch onto the mode selector slide. This explains why I had an OFF setting on the blower switch and mode selector slide (C41 only has off on the blower switch, C60 only has off on the mode selector). Just like under the hood, none of the factory wiring got hacked up installing it, just plug and play stuff.

 

I must be the only person who thinks that was done pretty well..... lol

I wonder how it would have cooled when compared to the factory stuff

 

For a kit that I assume included everything one would need to install AC into a car that didn't have it and make it appear normal to the untrained eye, it did the job well. Back when these cars were newer, you would've spent a small fortune adding an air conditioner to a non-AC car using GM parts, and I'm sure this kit was a very affordable alternative to that. My biggest problem with it was the wiring didn't look tidy at all, which could be on the installer rather than the manufacturer.

I would imagine it cooled on par with a factory AC system, it had extra insulation on the evap box near the exhaust manifold. Sanden compressors are pretty efficient. I mentioned seeing a similar system on a '90 RS, I test drove that car but decided not to buy it (way overpriced for it's condition) and the AC was plenty cold. Probably still had R12 in it.