AC rebuild questions r12 or r134a retrofit

[Trippcast98]

Long time lurker, first time poster.
I have a 1990 c1500 ext cab, 5.7&700r, when I got the truck there was tape on the hoses coming from where the compressor originally was and the compressor was bypassed with a free spinning pulley. I was told that th compressor gave out 5 years ago and he bypassed it and covered the hoses to avoid moisture entering the system. I grabbed a compressor off a buddy's part truck that is supposed to be in good working condition, it's the harrison 3090927 model and doesn't appear to have the connector on the upper rear of the compressor(max ac/recirc?) Can I just ground the connector or leave it disconnected.

On a side note, I found 7 14 ounce cans of original r12 for $100 bucks. Should I fill the system with r12 or retrofit it to r134a? If I do either what needs to be replaced or updated prior to filling a checking for leaks? Thanks for any insight, I live in Texas and definitely wanna start getting it all together before eit gets too hot.

 

[Erik the Awful]

I'd retrofit. When R12 shot up in price there was a lot of counterfeiting going on. Get the upgraded compressor and the retrofit fittings for R134a and you won't miss R12.

 

[Schurkey]

I have a 1990 c1500 ext cab, 5.7&700r, when I got the truck there was tape on the hoses coming from where the compressor originally was and the compressor was bypassed with a free spinning pulley... ...what needs to be replaced or updated prior to filling a checking for leaks?

In MY driveway, that truck would get a new orifice tube, a new receiver/dryer/accumulator, a new or rebuilt compressor, and replace EVERY O-ring AT MINIMUM. EVERYTHING re-used gets flushed with A/C solvent and a flush-gun, because the original compressor may have left shrapnel in the system when it died, and if you change to R134a, you'll have to remove every trace of R12 oil since the R12 oil isn't compatible with R134a refrigerant.

It would probably get a new condenser, maybe a new evaporator. And all that leaves is hoses and some switches. New "barrier" hose would be nice if you decide to go with R134a, since those molecules are smaller than R12 molecules, and can seep through the older "R12" hoses.

Guys say that "used" R12 hoses have absorbed so much refrigerant oil that they're no longer porous. I guess that's true...guys are successfully using old R12 hoses that are otherwise in good condition, with R134a refrigerant and oil.

Consider an add-on A/C refrigerant filter ahead of the compressor inlet.

 

[Ranger550]

I did a conversion on a late father's 1988 C-2500 with R-12. Replaced all the seals, flushed mineral oil out, dumped the condenser for a new one. Replaced the orfice/adapers Flushed the R-4 compressor, added 8 oz of PAG 150 and charged with R-134A. At idle she was putting out 42 F at the vents.

 

[L31MaxExpress]

In MY driveway, that truck would get a new orifice tube, a new receiver/dryer/accumulator, a new or rebuilt compressor, and replace EVERY O-ring AT MINIMUM. EVERYTHING re-used gets flushed with A/C solvent and a flush-gun, because the original compressor may have left shrapnel in the system when it died, and if you change to R134a, you'll have to remove every trace of R12 oil since the R12 oil isn't compatible with R134a refrigerant.

It would probably get a new condenser, maybe a new evaporator. And all that leaves is hoses and some switches. New "barrier" hose would be nice if you decide to go with R134a, since those molecules are smaller than R12 molecules, and can seep through the older "R12" hoses.

Guys say that "used" R12 hoses have absorbed so much refrigerant oil that they're no longer porous. I guess that's true...guys are successfully using old R12 hoses that are otherwise in good condition, with R134a refrigerant and oil.

Consider an add-on A/C refrigerant filter ahead of the compressor inlet.

I have never had much luck re-using hoses here on older vehicles. They tend to explode because they have degraded.