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R4 compressor running hot

martinsw on Fri April 04, 2008 12:40 AM User is offline

Year: 1979
Make: chevy
Model: corvette
Engine Size: 350 ls1
Refrigerant Type: R-134a
Ambient Temp: 60
Pressure Low: 25
Pressure High: 160
Country of Origin: United States

Car originally had ac but never worked. When I put in a new engine / tranny, I bit the bullet and bought ac manifold gages, orings, new drier, vac pump - cleanes system, evacuated, filled with 134a. The R4 compressor had a leak at the fan switch (didn't change that o-ring) - changed it and no apparent leaks. Seems to be working, got what looks to be reasonable high/low pressures, vents blow cold, al tube into compressor gets cold.

The thing is the body of the R4 gets really hot (to hot to hold a finger on). Is that normal, or maybe I have bad bearings in my R4??? Anyone know how hot the body of the R4 compressor should get when running?
Thanks, Steve

Dougflas on Fri April 04, 2008 6:29 AM User is offline

60 * is a little low to check pressures. Your pressures appear low but at 60* they may be ok. How much oil is in the system?

martinsw on Fri April 04, 2008 9:27 AM User is offline

I put 6.5 oz of ester oil in - system was totally open, I flushed condenser and evap, lines - new drier. The R4 was not new or rebuilt - pumped well when turned by hand, no roughness felt, drained all oil I could (laying it in various orientations overnight on bench) out before putting back together. I will recheck pressures when temp gets higher. Given the low temps I didn't want to overfil - would expect much higher high press in warm weather, and hopefully cool vent temps.

I did loose some oil from the bad oring - but it only appeared to be ~ 1/2 oz based upon where it puddled on the garage floor, so when I repaired the oring I added 1/2 oz oil back into the compressor before re-evac and refill w/~2.5 cans of R134a.

Is it normal for the body of the R4 compressors to get quite hot during operation? I could see how low oil could make it run hotter - maybe I lost more oil than I thought from the leak?

Edited: Fri April 04, 2008 at 9:29 AM by martinsw

Chick on Fri April 04, 2008 3:25 PM User is offlineView users profile

At that ambient temp, you are probably overcharged, wait for it to get around 70 to 75 degrees and rechaeck the pressures. 80% is only a guide, and it's nearly impossible to charge a retrofit under 70 degrees unless you have experience doing it.. High side on an 80 degree day would show the high side around 2.2 to 2.5 times ambient.. I would evacuate the system and recharge on a 70 degree day, starting with about 60% of the charge and "slowley" add until the suction line coming out of the evap is around the same temp, or cooler than the line going in (after the O tube of course)

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