I'm curious if anyone out there has rebuilt the ac/heater control unit in the center console? Or, if anyone has a used one they're willing to sell. I have a 75' coupe with AC that has a questionable controller. I'm not much of a mechanic, but when I took it in to get the AC working again...the estimate was HUGE! My controller is supposedly not working correctly to get the AC blowers to work and my mechanic recommends I replace the controller and that should solve the problems. Ebay hasn't brought the magic part yet...anybody got any suggestions?

Hey Randy, My 75 L-48 coupe doesn't have the AC, but I know that you can get the controller at Eckler's. Their controller with air is $74.99 for the kit.
Glenn

Have you ever done the rebuild? I don't know if it's difficult, or what original pieces stay and go. I'm pretty much of a novice, and I'd like to make sure I have everything I need before I start... I've seen kits range from $60 to $80 and was hoping maybe somebody out there has used one and has any advice?

Sorry Randy, I haven't done it yet. Mine works fine, but it is dirty. I just haven't gotten to it yet. Maybe this winter when I'm doing more of the interior stuff.

I have done it. It is very easy just take your time and it will be fine. Mine looks great. Brand new. I did have to replace the two swithes inside but corvette america had them instock so no prob.

I had my whole A/C system rebuilt last year. We ran in to a couple problems. One, if possible, use the old freon, vice the new. It runs colder in the older systems. I had mine upgraded without doing any research. You can still find the new freon, but it's more expensive. When I bought my 75, the compressor wasn't even hooked up and was frozen up. I replaced it with a rebuilt one and attempted to service it myself, but unless you are confident with working on the A/C, I would find someone to do it. Luckily, I work with someone that does a/c on the side. He basically removed everything from the car that had anything to do with A/C. He replaced the expansion valve and completely cleaned and purged the system. I installed headers which replaced the compressor mount and don't know if this caused the belt not to line up very good, but we had to shim the mount to get the A/C pulley to line up correctly. Even after getting the air to work, it was still hot coming out of the vents. We discovered that the heater core shutoff valve wasn't working correctly, which seems to be a common problem, so I installed a manually shutoff valve. This at least kept hot water from running through the heater core. The ducting on my 75 had a lot of leaks in it, so I spent some time up side down, with duct tape and putty, sealing all the leaks. The hi speed fan wasn't working, and I replaced the hi speed relay, only to find that less than 6 inches from the relay is a fuse, that was blown. After replacing the fuse, I was getting air out of vents registering 35 degrees F. We started with air coming out at 65 degrees. I also installed heat shielding under the carpet with really helps. I know I might have went overboard explaining what I did, but when I started this project, I just thought I needed to replace the compressor and add some refrigerant. Little did I know what bucket of worms I opened up. I wish I would have stayed with R12 refrigerant, but even with R134, it's nice to have cool air blowing out of the vents on a 90+ degree day.

Bill, Good Details! I took mine to a local Pep Boys when the mechanic there told me he had worked for a Corvette shop. We're running into many problems though. After flushing the system and re-charging with something called "Freeze 12" (supposedly an environmentally friendly R12 replacement)we found the controller switches worked sometimes, but either the switches or whole controller needs replaced. Once I got the car in my driveway, one of the hoses coming out of the back of the compressor blew out and I lost all my refrigerant, so now I'm back to square one and $200 in the negative! Hopefully they'll recharge it at a discount or for free, but I guess it's not their fault regarding the hose. Hey now I'm giving way too many details. I may have more questions for everyone soon, so please bear with me!

Are you talking about the line with the swivel on the back of the compressor? Mine leaked when we first installed refrigent. We finally got it to seat and hold fluid. The Freeze 12 seems to be a good product. I did some research on it, but I didn't know anything about it until we converted it over to 134. According to the information I read, it is compatible with both 12 and 134. It is supposed to be comparative with 12 as far as cold. When I service my system next spring, I was thinking about adding freeze 12 to it. I don't know much about Pep boys, as we don't have one locally here in Memphis, but NAPA does stock the fittings and hoses if you need replacements.

Randy, before replacing the AC/Htr control unit you should use a vacuum pump to check that it is truely bad. My AC checked out good by a serviceman but the AC was never very cold in the car. Turns out there were several problems similar to what Bill said on his. If you are sure you have tight shutoff for the coolant to the heater core, then, check the bowden cable that connects to the hot/cold lever on the control panel. When you move to the cold position you should feel some resistance, if not adjust by turning the turnbuckle. This cable connects to a door that bypasses the heater matrix. I believe mine was not completely closing and was mixing hot and cold air. Also the small black vacuum line that comes through the firewall is real easy to break or have breaks that are not noticable. Mine was cracked a quarter inch before entering the firewall and not noticable until I put a vacuum pump on the line and could not hold any vacuum. Good luck, vacuum is king on these cars.

I agree with the above. Look for vacuum leaks and repair, controller may be fine. Dr Rebuild has the control valve if it is indeed bad. I definately agree to stay with R12. If you don't, get R134. Any of the other substitutes are not good IMHO. Some are butane, which you don't want in your engine compartment. Others have extremely different size molecules (R12 and R134 have the same size). An A/C expert once said these substitutes have molecules as different in size as BBs and Golf balls. Over time the "BBs" leak out leaving the "Golf Balls". The chemical balance is now out of whack and cannot be corrected by adding more refigerant, it must be evacuated and replaced. In an R12 or R134 system if the system gets low you can add more.