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A/C conversion to R134A info request

John Ulrich

Well-known member
Oct 15, 2000
Eagan, MN, Scottsdale AZ
1981 Two Tone Claret, 2014 CRT Roadster
Needing to repair the A/C in an '81.
I've read the article on "Retrofitting to R134A in the forum.

Any feedback from readers on successes or Boo-Boos incountered.

The guys in the local shops make it seem like a "piece of cake" ...........That's when I
get worried!!!!

Thanks for the input!
AC upgrade

I had the 78's done about 3 years ago. Installation was not a problem...any reputable AC shop will be able to do a good job. The problem I encountered, is the AC made the engine temp climb to 240 degrees when the AC was on!
So...I didn't use the AC. :(
I thought of different radiators, electric fans, higher volume water pumps, etc...then we moved to WA, where I didn't need AC and I didn't use it for 2 years. (I'd turn it on for short periods just to keep things moving) We moved to GA this year, and a few weeks ago I used the AC for about 20+ minutes while driving at 45mph and had no temperature rise. The only difference between three years ago and now: I have added "Water Wetter" and the area's local climate is markedly different...and I guess not driving at 70mph on CA freeways helps, too!
So, now I'm happy to know I can use the AC when around town, at least! I'm sure I'm gonna need it, here in the South!
A/C R134 conversion


I recently had to replace the A/C compressor in my 86 L98. I had it done by Chris at Corvette Doctor in St Pete, Florida. He recommended the conversion and said the R134 was more efficient in the corvette than the old R12. He was right! I have the electronic A/C control panel and I have to keep moving the auto temp up....
it's too cold! That sounds like a contradiction here in Florida. Bonus, R134 replacement is a lot cheaper than R12.
A/C retro-fit

I just did my 1980 from R-12 to R-134a, did it myshelf. Not too bad. Recommend replacing the accumulater and vacuming down the system (by a shop) then putting in your own retrofit kit.
It runs about 45 degress at the vents now in 85 deg. weather. Spent about $100 total. Not too bad!

Buy a pressure gauge, read some manuals, ask questions. Make sure the oil in your system is the right kind (ester, or mineral oil) and the right amount. R-4 commpressor only takes 6 ounces of oil total.

Do not overfill your system! will make it worse. Takes about 3 1/2 cans or R-134a (12oz. cans)

R-12 here costs $39.95 a 12oz. can with a liscense to buy:eek :eek that's insane. R-134a costs $4.95 a can:)

I am not an expert by any means on A/C work, and I did it.
I want to put 134 in my '73. I understand the VIR type system used that year does not work like the others. Can I just add the 134 or do I have to convert to a different style system?
I changed over to 134a in my 77 and had no problems. A local shop removed the old 12 from my system for free as they kept the freon to recycle and sell to another user. I then installed the new fittings and the 134a myself. At first I was not happy with the air temp. Then I added a 3oz can of Max Cool additive, that made a major difference in the air temp. Total cost of conversion= $48.50
I'm now on the second year and no problems and still driving cool. Rick

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