billschroeder5842

My AC system is not functioning at the moment. That's Ok as it is cooling off in Texas, but I'd like to have that "in the mill."

Becasue the car is a 1991, it is R12 so it is a bit trickier.

Is it better to convert to 134 or refill with R12?

Converting is a longer term solution but what is required and is it worth the effort as I can get all the R12 I need for no more than 100.

Thoughts?

FASTAZU

Had my 91 converted to 134 and it works ok, I think it cooled better with R12.

zr1fred

Your 91 was pretty much designed for 134 with the larger air handling duct work. R12 does cool better, but not that much better. After 20+ years, most older cars have been successfully changed long ago to R134 with none of the doom and gloom stories of years ago. Its a very simple process, and you can buy the conversion kits at just about any auto parts store (even Walmart). And 134 must have saved the planet, you don't hear any more holes in the ozone stories (although there is those pesky R12 patent expiration stories).

billschroeder5842

So, just a 134 conversion kit? No additional parts or compressor work?

I ask as my 82 required a few pieces for the swap.

Thanks!

Goldcylon

Id stick with R12 if you can get it. For conversions R12 just cools better

mike100

Let us know what the conversion entails if you go that route...I'm still on R12.

zr1fred

134 has smaller molecules, so it tends to leak out more than R12. But time has shown its not a big problem. Anyway, your system is 25 years old so it probably seeps out anyway. The other concern was the compressor oil compatibility, but the new kits have taken care of that issue eliminating the need to flush the system as was once thought. Again, most pre 95 cars were converted successfully years ago, so much so its very rare to find one that hasn't been changed over, mainly collector cars that are rarely driven. A lot of times they didn't leave the 134 connector adapters on, or used a "drop in cocktail" from swap meets, so its hard saying exactly what is in your system now. There is a good chance you have something other than R12 in there now. There is a lot of information on the internet, and its been discussed many times (not so often anymore) here on the forum.

Goldcylon

Normally it involves injecting that conversion Pag oil and changing over the fittings. However from my experience its just never works as good as R-12. New systems with 134 work pretty well.

G8nightman

Stay R12

Goldcylon

What he said

ZR1Bob

Talk with Marc Haibeck about this. Back in the 90s GM put out a service bulletin that said you could convert to 134 without changing any of the seals. Just make sure the system is completely evacuated of the old R12. I had Marc change my '93 to 134 and never had a problem through all my years of ownership. I believe my '95 came from the factory with 134 but not certain. --Bob

Goldcylon

MY 94 was the first year of 134A in the C4 Corvette. So yes your 95 ZR-1 was 134A OEM equipped. GC

zr1fred

I've had 90- 94 and 94 up C4s including ZR-1s, and haven't noticed any real difference in cooling. The ac systems are exactly the same except for the refrigerant (with the possible exception of minor hose and seal material and controller changes). Some people don't want the conversion adapters and stickers on an otherwise original car. Some people don't want the hassle of locating R12. What ever works for you .

Scrrem

I still have a decent supply of R12 so I have never converted my 90 over, but finding R12 at a reasonable price is not easy anymore.
I wouldn't convert if the system was still functioning. But now that you have to open it up anyway it's a perfect time to replace ALL "O" rings and hoses (if needed) and change it over to 134.
Rich

billschroeder5842

Thanks- I took your advise and called Mark today (super nice guy) and he confirmed that the system will need the 134A fittings and appropriate PAG, evacuation, fill and good to go.

I found the fittings at Auto Zone for 12 bucks. I'll give this a shot this weekend.

I'll keep you posted!

-=Jeff=-

I found more drag on the motor with R134a. I have since cleaned out the system and switched back to R12,

I do know that the Condenser was changed when GM went to R134a.. R12 was Tube & Fin, 134 is Parallel flow.. I swapped to a parallel flow with R12 and it seems to work well