Question about AC Compressors

Hello. I recently bought a new AC compressor at an awesome discount. It's an FS10 compressor, made by Visteon. The compressor looks great. Now for my question.

I am basically rebuilding the entire system. I was planning to use either R12 or R406a in the system, because I want good performance and don't really want to change the condenser, and I know the condensers are designed differently for R-134a systems. This compressor came with PAG46 oil in it. It also came with a label stating "R-134a required."

My question is, do you think there is something in the design of the compressor that makes it unusable with anything but R-134a? Or is it labeled just because of the oil that's in it? Couldn't I drain the oil and put mineral oil instead to use it with R-12?

That is a good question for the manufacture to answer. I have replace several for people & they used to be labeled for both types. The R-12 condenser will work with any refrigerant you go with. It does come down to the climate it will be working in. Looks like your in PA. you should be good. If it were 95-110F it might struggle to keep you cool.

Yes, putting r-12 or r-406a in will ruin the oil. Was there r-12 in it before? You can drain the oil and use different oil. R-12 has a better cooling effect but is toxic to the ozone which is why oem is 134a. If your system was r-12 and you are using 134, A different expansion valve, more restrictive, can change the system by lowering the pressure, boiling point, in the evaporator and increasing the pressure in the condenser. It would slow the system down giving it more time to exchange heat. The down side is it takes longer to start cooling. I dont have a lot of experience with auto a/c units. Usually they leak. The more hard lines you can use, the better the system will seal. If you cant get the system sealed, you cant pull a vacuum. Thats important. Otherwise you are using the boiling points at barometric pressure.

The FS10 is the original part for the 90 model using R12. As long as you drain out whats in there and use mineral oil, you will be OK. You don't have to freak out if an oz of PAG is left in the compressor. It will settle at the bottom of the lines or accumulator and just sit there.

Ok, guys. Thanks for the help!

I thought the compressor should be okay with either type of refrigerant. I mean, the car came with R12, so why would a direct replacement only work with R134a? I just can't think of a good reason. Interestingly, I found another forum with a question just like mine. Same sticker and everything.

http://www.autoacforum.com/messageview.cfm?catid=4&threadid=20715

Just to clarify, my compressor is brand new in box. Got a smoking deal on a closeout - under $100 to my door. So there won't be any contamination or anything. I guess I will just dump out what is in there, then run some mineral oil through it, then add the proper amount of clean mineral oil.

I want to stick with R12 (or similar) because I don't want to mess with replacing orifice tubes, pressure switches, condensers, and who knows what else.

I want to put brand new "barrier" hoses on all the soft parts to keep leakage to an absolute minimum. (They supposedly seal to a smaller micron level, which is required to keep R134a in the system year after year, and helps for R12.) I bought a new liquid line with orifice tube included already. I havent't decided yet whether I will buy a new suction/discharge line, send it out for soft part replacement, or buy the crimping tool and redo it myself. (The tool is over $150, but I could possibly start redoing lines for board members and make back some of the money.)

So, with a new accumulator/drier, hoses, o-rings, and a new compressor, I plan to flush the 2 heat exchangers, and let them dry out. Then rent a vacuum pump (if possible!), install the new parts, pull a vacuum immediately, make sure it seals ... and then charge.

I Would use nitrogen to flush out the cores after you do a flush with what ever you plan on using.

you can also use nitrogen to check for leaks, this is bennificial on finding leaks on the high side. i have seen many leaks not leak when vacuum is applied but when you start to charge the system and 100psi hits them they leak like there is no oring there.

new hoses ect will go along way in the system.

but in reality i have used r134 retrofits on bmws here and have no strange side effects we get over 95 -100 in summer and no problems. yes r12 might be slightly better but you have to weight the pros and cons and being able to get r134 anywhere is a big..... plus.

90turbo1 said:

I Would use nitrogen to flush out the cores after you do a flush with what ever you plan on using.

...

but in reality i have used r134 retrofits on bmws here and have no strange side effects we get over 95 -100 in summer and no problems. yes r12 might be slightly better but you have to weight the pros and cons and being able to get r134 anywhere is a big..... plus.

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Thanks for the suggestions. I assume that I can get nitrogen at a welding supply shop. What sort of adapter fittings do I need? I believe that R12 fittings at tank and car are SAE 1/4" flare fitting with 7/16"-20 threads, right? And R134a fittings are 1/2" Acme threaded fittings? So what do nitrogen valves use?

I may end up using R134a in the end. I feel like the cost is sort of moot, IF I can get the system working right and really sealed well. I don't mind buying R12 once, just don't want to buy it every year.

S_Mazza said:

Thanks for the suggestions. I assume that I can get nitrogen at a welding supply shop. What sort of adapter fittings do I need? I believe that R12 fittings at tank and car are SAE 1/4" flare fitting with 7/16"-20 threads, right? And R134a fittings are 1/2" Acme threaded fittings? So what do nitrogen valves use?

I may end up using R134a in the end. I feel like the cost is sort of moot, IF I can get the system working right and really sealed well. I don't mind buying R12 once, just don't want to buy it every year.

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Also, I am thinking about getting the HVAC certification so I can just buy the refrigerant myself. I don't have to worry about refrigerant recovery equipment for now, as the system has been empty since before I bought the car!

90turbo1 said:

but in reality i have used r134 retrofits on bmws here and have no strange side effects we get over 95 -100 in summer and no problems..

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I had to replace the compressor shaft seal after 7 years of duty on my white car. I took the opportunity to install an orange O-tube; charged it up using a low side cycling pressure of 20 psi and hit the sweet spot.. 40 degrees out the vents... Ahhhhh.