One of the last major things I had to do on my 1982 CFI Corvette project was to "fix" the HVAC problem; more precisely, the lack thereof. I wanted to keep the R-12 system, for no other reason other than the fact that all the original system parts were in place, and they appeared functional. This deduction was made based on a visual inspection only, I would know more when I introduced some Freon into the system and turned it on for the first time in, god only knows, many years.

Not being an HVAC expert, but good at replacing parts until I eliminated all possibilities that would cause the problem, I chose a more sensible solution and sought the advice of a professional. My choice, Mr. Artic Air, did a partial charge (wanted to save the gas in case their was leaks in the 30 year old system). This action initiated the low pressure switch (good) and allowed the compressor clutch to engage (great). All seemed to go well with the exception of warm air blowing on my feet and no air coming from the upper vents (not good). Right away Mr. Artic Air unceremoniously declared I had a vacuum leak and that the dash would have to come out for him to adequately trace the tubing down to find the problem…at the hourly rate of $75. But don't worry, "I have been doing this type of work for 40 years."

Wait a minute! Hold up! Let’s remove the glove box and look in their first and see if we can identify any problems first before removing that dash. I know I am the novice here, but I am not a gullible dumb *** either. I must confess I am the one who looks for the simple solutions first. Past experience has taught me (at cost) to analyze the problem from all angles, identify what components make up the system, determine how they are linked and then deduce what could cause the existing condition; in this case, hot air cooking my feet. Mr. Artic Air didn’t want to hear theory, he just wanted to tear down and replace with new (which would have worked…but, as it turns out, was not necessary) at a tidy profit. Not wanting to **** off Mr. Artic Air (I did need his R-12, which as you may no is somewhat hard to obtain); I said I would return in a few days with either the vacuum problem fixed or the dash removed so he could trace vacuum issues and make necessary corrections.

I missed something in the previous paragraph I need to mention. I, the unskilled HVAC man, noticed the bypass valve vacuum switch was not being controlled by the flapper control lever due to maladjustment. I had reason to believe that nothing else had been changed in the original system and all the vacuum tubing (at least inside the cab) was in very good condition with color coding still etched on the tubing. Returning home and cranking up the old 'puter I began a research on automotive HVAC systems. By the end of my “training” I was convinced that the bypass valve vacuum switch was the weak link (it is the only component made out of plastic). Readjusting the cable adjusting turnbuckle so that the plunger was seated inside the vacuum switch casing (where the lever was pulled all the way to the left (cold) on the climate control module), I started the engine, flipped on the A/C MAX and turned on the blower to high. After a minute, the upper vents opened up and cool fresh air entered the cabin (and some aged dust full of carcinogens). I still must return to Mr. Artic Air to recharge the system to full and I will still be monitoring for possible leaks, but, for all practical purposes, the HVAC is operational. I still have the rest of winter to test for reliability of the system. I live in Florida and it gets hot. Even with the T-tops off you still need to have the A/C on if you want to stay cool and comfortable.

In the picture below you can see the flapper control lever (rusty metal) making contact with the bypass valve vacuum switch (yellow plastic) and this is viewed through through the glove box opening. It is a tight fit, but doable.



P.S. The cost was zero dollars to repair system. The Freon will run me about $50-75 depending on how Mr. Artic Air, guardian of the R-12 gas, feels that day. Moral of the story is to read the schematics and pick the weak link in the system first, then move on.

 

Yep! That's how I fixed my A/C problem a few years back. Went from 68 out of the vents to 28.

That vacuum switch controls the hot water from the engine to the ventilation system. If that button is not depressed it will have a continuous flow of hot water going to the ventilation system.

 

I love it when a plan comes together! After finishing this rebuild over the past year I can, categorically say, I know the workings of a 1982 CFI corvette coup and am ready to do another.

 

Thanks for posting this. I had my A/C recharged after I bought my Corvette and a few months later it was cooling intermittently and I think something like this is probably causing it. I'll try to check it out in the summer, but I have a hard time following what you were talking about, lol.

 

scorpion18z,
Thanks for that usefull post!

 

This should help:

 

Wow, thanks so much, Yellow1980!

 

Yepper! That is what I was trying to say with all those words. I do like the picture story better and would like to get ahold of a camera like the one you are using. Also, how are you going about all the labeling? Very nice presentation. Are you a Power Point Ranger?

 

Thanks again to the both of you. I've been really frustrated that I searched hard to find the Corvette I wanted with factory a/c and now its not working properly. I really don't trust the automotive a/c guys to know anything about it on an old Corvette beyond seeing if its full of freon and the compressor is working so I'm thrilled you've given me some of the key things that can go wrong other than that that I can check out for myself.

 

Thanks Yellow1980 & scorpion18z

 

You can still buy R12 although it ain't cheap!

Search Ebay for R-12 refrigerant.

Andy

 

I use PhotoShop Elements to crop pics and add text and arrows.

 

I will keep that in mind the next time around if I successfully fix a worthwhile problem...maybe tomorrow (lol).

 

Yep! I had 2.75 lbs in, an orifice and o-ring for $200