A/C R134 conversion

[Meridivs]

Hello,

We need to convert a '91 Pontiac TS 3.1 TBI A / C system from R12 to R134.

Have anyone done it with success?

How much R134 is needed to charge the system (same as the original R12 quantity or less)?

Anything else we should pay attention to?

Many thanks!

[procaddytech]

The proper R134 charge is the R-12 charge times .9 then subtract .25 lbs. For intance a 2.50 lb R-12 charge would require: 2.5 x 0.9 = 2.25 then 2.25 - 0.25 = 2.00lbs R134. Conversion can be done successfully. All of the R-12 will need to be properly recovered. The compressor should be removed and drained of as much oil as possible. The accumulator will need to be replaced with one with an R134 compatible dessicant. You will need to buy a conversion kit. Remove the schader valves from the R-12 fittings and screw on the R134 fittings. Add the proper amount of PAG or universal compressor oil to the compressor and system. If the existing rubber hoses are not torn do not replace them because the R12 oil helps seal the pores in the hoses.

[LMP]

THis from another thread:
If you plan on retrofitting to R-134a you should replace all the O-rings, install new charge fittings, a new dryer, bring it to an A/C shop to have them check your work and get the system flushed and charged. GL

On this forum or a parent forum (maybe lumina APV), there have been a few threads about refrigerant R143a....yes 143, not 134, that can be used as a direct replacement for R12. I do not know about its availability but I think remembering that was from a member living in EUrope. MAy be verify this option.....
ALso, a rerigerant sold as "RED TEK refrigerant" is available in Canada and sold as a direct replacement for R-12 at Canadian Tire.

EDIT: ahh....verify this
http://www.redtek.com/win_12a_faq.html
http://www.canadiantire.ca/AST%2Fbro...bmLocale=fr_CA

[500hpgtx]

Earlier this year, our 95 TS 3.8 had a slow leak. I went to autozone, and used their leak seal freon, along with a new type of freon . I believe it was called Sub zero. I do not know for certain. What I can tell you is that it works as advertised. I can't believe how much colder the air conditioner is. My pontiac(GMC now) mechanic friend said that the freon is the new synthetic stuff.

[Meridivs]

Interesting, I remember going to some similar threads about R134 conversions but couldn't remember where exactly.

procaddytech, thank you for the very useful formula!

500hpgtx sounds good but we are in Europe and getting the AutoZone here would be pretty difficult

LMP, I will check what you said about the R143a. Btw, do you currently use the R134 or another alternative refrigerant in your A/C system?

[LMP]

Originally Posted by Meridivs

LMP, .. do you currently use the R134 or another alternative refrigerant in your A/C system?

My '93 TS 3.8 originally came with R134. then in 1997, the condenser radiator (aluminum) failed. It was replaced with a copper radiator and refilled with R134. Still operational.....mmm..I hope....did not try it this year yet, have to reinstall the long serpentine belt ; as soon as warm temps fade away, summer is short here...I remove the long belt and use a shorter belt to bypass the A/C compressor...the clutch is noisy when free wheeling.

[Meridivs]

Thank you all for the valuable input.

I have made the conversion to R134 and it's working for now. If anything goes wrong I keep a spare Accumulator/Compressor as backup.

Interesting thing with the A/C bypass on the 3.8 TS. Unfortunately mine still has engine oil pressure issues (changed Oil Pressure sensor so far), if we'll figure that out then maybe we'll start putting some money into it if it's worth it (engine ok).