R12 to R134a conversion

Hello,

I have a 1994 Chevy s-10 blazer which was originally an r12 system. I brought it to the auto shop last year and was told that this would probably be the last year that I could get r12 from this shop. It is too expensive and he will not be buying another bottle of r12 when his runs out. I decided to have it changed over to 134a. 3 reasons 1) its cheaper $$ 2) I could do it myself $$ 3) the shop was not going to carry r12 anymore and this is becoming the trend. After the coversion (2 weeks later) the compressor went bad (ball bearings went). I brought it back to the shop because I thought he did not put enough oil in the system. He stated he did and that r134a conversions do this all the time. An r12 compressor is not designed for 134a and these coversions never work after a year or so the bearings always go mine just went sooner. Well I replaced the compressor and went to another shop, they stated the r134a is fine in an r12 system so I had them evacuate and refill the system with r134a. When I run the AC I get a little bit of a whinning noise w/ a metal rattle when the AC is on and it goes away when the AC is off. First what does anyone think of r12 to 134a coversions. 2nd should I add an extra ounce or 2 of oil to the system to help protect against the bearings going again and maybe solve the metal rattle/whinning when the AC is turned on???

Thanks for the replies.

The only thing that I have heard and done is that a retrofit oil needs to be put into the system before you put in the 134 and after system if vacuumed. My friend has not had any problems with his. If it is not vacuumed and new oil put in, then you will have problems.

Needed to add, that the filter and valve need to also be replaced in case they are bad when a compressor is replaced.

I replaced the R12 with R134 in my Park Avenue, and I haven't had any problems. Its been two years now.

Did a conversion on my 88 Camaro, not nearly as cold as the R12. Note that if you got a rebuilt compressor they do tend to make various noises. Not sure what is involved in rebuilding but for the low price I'd guess they are slapped together pretty sloppy. If it works you'll be ok for several years. From what I've seen of the rebuilds they do last a while even when noisy.

I converted my 86 IROC-Z, my 85 4x4 Blazer, and my 72 Buick Skylark to R-134a, all with no problems (no compressor failure or anything). It doesn't seem to be as cold as R-12, I agree, but I'm okay with that as long as I have ozone to protect me from radiation when I go outside. :iceslolan

My 98 Blazer has a weird sound that is only present when the fan is on, but that it the blower motor whining a little - always did it since I owned the Blazer (over 2 years now). Does your noise still seem to be there even when the fan is on the settings that don't use the A/C? If so, it could be the blower motor instead of the compressor. Also, is your belt as tight as it should be? I sometimes get a whiney metal noise from loose belts. I don't know if the 94 has a main serpentine belt or individual belts for the compressor, smog pump, alternator, etc., but the 98 has one big belt that is auto adjusted with a big tensioner and the 85 has individual belts that need to be tightened manually.

As for adding oil to R-134a systems, I add the oil at the same time as the refrigerant - you don't have to do it before. It even comes in the can with the R-134a and stop-leak, so there is no way for me to add it before, even if I wanted to...