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Compressor won't cycle

Shoojohn8 on Sun June 15, 2008 12:47 PM User is offline

Year: '96
Make: volvo
Model: 850
Engine Size: 2.1 L
Refrigerant Type: R-134a
Ambient Temp: 80
Pressure Low: 35
Pressure High: N/A
Country of Origin: United States

My wife and I love our volvo until I have to work on it.

last year the A/C started failing, the compressor would cycle fast and the there was intermittent cold air through the vent, I looked on line and read all the DIY hand can of R-134a with a pressure gauge. This was my first big mistake. filled the system so the the compressor cut in at ~25 psig and out at ~40 psig, this returned some performance and got us through the summer.

This spring, determined to not piss my wife off with a failed a/c, I took it to a shop and asked how much to fix it. two hours later, $2800 and a week of work!!!!! My jaw hit the floor. "It needs a new evaporator and its over full so a compleat system tare down and clean. " This guy is nuts to think I can afford that kind of outlay without real proof, he sticks a coolant leak detector in the running a/c vent and it beeps. Oh S*%t he is right. evap is leaking and I'm in for a big ride.

So off to the big W.W.W. I go to see what I'm in for and changing the evaporator core IS A BIG JOB. but I figure for that kind of money, I can get the tools and fix it and still have the tools. and fix others a/c,
A real win for me that when looking for good prices and decent quality tools I found ACKITS. YES!
I think this is by far the best A/C forum on the web.

I examined the system with my UV light, not a sign of dye anywhere. not even in this filler cap?? Well lets order anyway. A starter kit, a scale, ( fill by weight ) a evap core, a accumulator and office, oil and O rings, and a compressor, all the things quoted. find a weekend and get to work.

first lets dye the thing and see what shows up. NOTHING! ??? not a leak after a day of use. a spot here and there but wait, the back of the compressor All hoses, fittings and lines look good. Had the system pumped out at a shop. RECYCLE, don't pollute. Pulled a vacuum for an hour and let it sit for an hour, not a leak. Cool, this is not so bad, lets refill! added the 1.63 Lb of R-134a ( what the sticker indicated) and go.

everything worked except the compressor stoped after an hour or so and did not restart for a few minutes. Thermal switch? its got one on the back or is it the clutch? did the fuse diagnosis i read about here and it was working good. This car does not have a high side port so the high reading is out.
Low side is steady at 33 psig and the compressor does not cycle at idle but does after driving a few miles.

So this weekend i borrowed a evacuator w/filer, got a recovery tank ( my wallet is empty) and pulled 1.65 Lb of coolant out of the system. replacer the accumulator, office and compressor. Sure enough there was debrey an the office filter, bad compressor. flushed the condenser and evap, added new oil (PAG 46)to all the components ( VADIS give amounts to add in each ) Pull down two Hr and let sit an Hr ( I only had compressed air, not Nitrogen to clean out the flush) no chang in vacuum. pumped down again 30 minuets and put 1.65 Lb back in.

NOW the compressor does not cycle at idle , drove it a half hr and it cycled a few times and went back to being on all the time. Low side is steady at 33 psi, cools down to 38 deg at vent, Amb of 78 deg, 4 deg difference between evap in and out, 35 deg difference on condenser. and I feel I have missed something!

What do i do now, if anything

Thank you all so much for sharing your knowledge,

Because I’m not this guy

fonebone on Sun June 15, 2008 7:13 PM User is offline

Hi Shoojohn8; I'd say sit back and enjoy a well done job! A Volvo was never a good AC car, from my experience-newer ones seem improved, from what I gather. As ambient temps go up, you should cool fine. from your info. 38 degrees on a Volvo is darn good. Please follow up with updates if things are OK, as I'm sure they will be. Always good to hear a success story!

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