GBousley

Hello, all! I need tom replace the a/c compressor on my 1992 bird. About a year ago, I remember reading that the stock replacement compressor must be set up differently to run R134a.. use a different oil, etc? I can't remember and I cannot find the information. Can someone help square me away, tell me what I need to do to replace this compressor? The system has already been converted to r134a, as I can get a standard refill hose on the line to "recharge" the system. I just have a bad seal on the compressor and the freon escapes..

Thanks!

GBousley

Found this old thread asking a similar question: https://www.thirdgen.org/forums/tech...essor-car.html

The response was to use an oil that can be used in an R12 and r134a system. Is that all I need to to ensure the new R4 compressor will run with r134a?

Will most likely be buying this compressor:

Scotty54

I have been digging on the 'net for information on this myself, and have a knowledgeable friend to confirm/deny some of my findings. My 91 Formula was converted by the PO and I am still dealing with AC problems two years later. I have taken this opportunity to learn how to do this myself, and buy the necessary tools.

While a swap to R-134 can be accomplished easily, a little more effort will maximize cooling and any potential negative effects. One of those is flushing old oil from the system and replacing it with the proper PAG oil recommended by GM for the R-4 compressor.

While I can't advise on how to do this (I haven't done it myself) there are plenty of YT videos out there.

GBousley

So, doing some research, watching videos, etc. Retrofitting r134a into an r12 system seems to mainly be about the fittings and the oil. The fittings seems easy enough, but I'm worried about the oil. I'll call ACCelco and find out what oil is recommended for that compressor, but also I'm finding some mixed results on how much oil. Some sources say to put more or less depending on how many new parts you replace, ie: compressor + dryer, etc. Any thoughts?

GBousley

Getting a lot of good info from this vid:

Scotty54

GB - I found two different charts online showing PAG 150 as the recommended oil for the GM R-4 compressor and R-134. That's what I am using but please verify for yourself. Since mine has already been converted and for a time was working well, I am assuming that it was properly flushed. My current problem is a BRAND NEW evaporator from Rock Auto that lasted two months before springing a leak. And the replacement arrived damaged - no packing material in the box.

1989karr

The R4 compressors generally don't come with oil in them. Youd have to confirm by what the manufacturer says or by checking the compressor you get.... .I normally just put 6 ounces of dye / PAG150 oil (i buy the delco units, and 6 oz are recommended) straight into one of the ports the lines go to, rotate the compressor clutch by hand a few times and button it up.


Since your system is already converted there is probably oil everywhere. in the system. Personally in this case I just add 6 oz to a dry compressor.


If all the parts are new I add 1 oz to all the other parts as well as the 6 to the compressor...is it the best way? probably not, but I don;t have the equipment to remove al lthe oil etc...


No problems in many years of doing this. .

GBousley

Thanks! I'll be doing the work over the weekend and will follow your advice.

So, to make sure, add the 6 oz of PAG to the line, don't just pour into the compressor?

1989karr

No prob.

But no, right into the compressor. (where the ac lines would bolt up to)


Uness your compressor comes with one, you'll also likely need to remove a snap ring and plug and install a pressure sensor on the compressor from the old one........ be sure to replace the o ring with a new one as the one in there likes to leak.

GBousley

Thanks! So, I did the work and replaced the compressor, dryer, orifice tube. Added 6oz pag oil to compressor, vacuumed the system and added the freon. (r134a). Air blows very cold!

So, something did happen to muddy the water, as always... my ac guages were waterlogged (Stored in a toolbox that got FILLED with rain water.. i know, I know). So, I dried them in the sun, and made sure all water was out of hoses, etc before performing the job of vacuuming and refilling... just hoping I didn't mess up and get moisture / water in the system.

Question: Should my RPMs jump up when AC is engaged? Also, should the compressor be very hot to the touch?

Here's a video of my car idling when AC is turned on/off. thoughts?

1989karr

the idle will jump a bit when the compressor engages... the IAC idles the ngine up to keep the idle / engine running correctly .

Yes, the compressor will get rather hot! In fact the condenser / hot line will also get hot as well




I doubt you put oisture into the system.... if anything when you vacuumed it out, all the moisture would have gone inti the vacuum pump lol