Refrigerant ?

[MR2Jedi]

Going to refill A/C compressor since I drained it when I did rebuild. Which refrigerant should a '91 MR2 Turbo use?
I guess it used to use R22 but they changed didn't they. .......134a?

[Dave's]

Would have been R12. R22 commonly used for homes. But yes, 134a is used in cars now. Change your seals/O-rings and I think you can use it in an old system OK. Not that I'm an expert but I'm pretty sure that's the case.

[MR2Jedi]

OK, thanks for the correction. I knew it was something like that..
134a it is.. Thank you

[Ghostyman]

They came stock with R12. If you still have the stock A/C system in place, refill it with R12. You can buy it relatively cheaply on eBay.

R134a is the "new" refrigerant. It doesn't cool as well as R12 and will make your A/C fail early unless you do a complete (read as "expensive") overhaul of the A/C system. Environmental concerns are the reason that cars switched from R12 to R134a but people are now finding that R134a isn't that much better.

Early gen2s are still covered under a safety campaign for the AC expansion valve. If you haven't had the dealership do it yet, they will replace your expansion valve and refill the system for free. If you have R12, you can insist that they refill it with R12, otherwise they might convert you to R134a.

[MR2Jedi]

I just bought a manifold gauge set for R134a! Or will it fit the R12 too?

[Ghostyman]

Originally Posted by MR2Jedi

I just bought a manifold gauge set for R134a! Or will it fit the R12 too?

No. One of the requirements of changing from R12 to R134a is replacing the fittings. They (DuPont & the EPA) wanted to make sure you couldn't accidentally mix them as they aren't compatible with each other.

I recommend everyone who has R12 keep it for as long as possible. Initially there were fears that R12 would become prohibitively expensive but it's available on eBay for about $20 per 12oz can. I forget the capacity but I don't think you'll need more than 2 cans.

R134a costs about half as much as R12, maybe a bit less. Still not worth it.

Side note, R134a is much smaller than R12 and will leak easier.

[MR2Jedi]

Originally Posted by Ghostyman

No. One of the requirements of changing from R12 to R134a is replacing the fittings. They (DuPont & the EPA) wanted to make sure you couldn't accidentally mix them as they aren't compatible with each other.

The fittings you speak of are the A/C High and low pressuse fittings in the frunk?

[Ghostyman]

Yep.