Volvo RWD 900 Forum

I replace the compressor with a rebuilt and put in three cans of r134. Now it puts out cool air but not quite as cool as the old compressor did. The low side pressure reads 45-55, which I understand is high. Should I bleed out some 134a to get the pressure down and improve ac performance?

The guy at the compressor rebuild shop says I have too little R134 and to slowly add until the pressure comes down to the correct range. I'll try it this weekend.

I added more and the pressure kept going up. I talked to him again and he was frustrated when I told him there was no place to read the high side. They are sending me another compressor.

Hi Philip,
I'm wondering why you ignored the advice from "dewfpo"? He was quoting right out of the Volvo manual.

I'm also wondering why you elected to replace a compressor that was "working"? The control works by cycling the compressor to keep a constant pressure drop range at the dryer/reciever. There is no need for a high side pressure reading. Your "advisor" doesn't seem to know how the new Volvo system works. He is assuming the functionality of an older system I think.

In order for the cooling to be optimal in this system you need the proper amount (weight) of R134a and compatible oil in the system. You didn't mention any oil, a new orfice, or new dryer/reciever in your system repair.

I replaced my compressor several years ago because the oil got low leaking by case seals in the compresssor housing. This in turn caused a lot of friction and resulted in broken links at the clutch. At the time of the repalcement I put in new 'O" rings, a new orfic, a reciever/dryer, and replentised the PAG oil. This was followed by a good "vacuuming" and finally with the proper amount of R134a. The system performed flawlessly for a couple more years until the condensor got a hole in it from corrosion. I found the hole using florising dye and a black light. This time after replacing the condensor I only vacuumed the system and installed the amount of R134a as described by dewfpo. I now have a slow leak that I haven't been able to find such that every other year I've been vacuuming the system and replacing the R134a by weight. System has continued to work well with about 41 F degree air from the vents after installing the R134a.
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'96 965, 16' wheels, Michelin Pilot Sports, rear 18mm bar + Koni, 201 HP cams, 149K. Put 200K on '85 745 TD.

Let's see, the system on a 960 takes 1.96 lbs or 31.36 ounces of R134a. The cans I have are 12 oz cans which means (if yours are the same size) that you installed 36 ounces or 4.64 ounces too many. That's 15% too much. R134a systems are not as forgiving about overcharging than R12 systems. You may gain some cooling efficiency back by removing the excess.

DEWFPO
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1998 S90 083,228 and 1995 964 154,100