This is a story of “don’t do what I just did”.
My AC system has a leak, as do most early V70s and 850s. For the past 2 years, I have been adding a can of R134a about once a month during the summer and this just barely makes the cooling system tolerable when the outside temp is above 85.
This week, I prepared to drive to Columbus, OH, to pick up my daughter from school. It is already in the 70’s down there, so I decided to “charge” the AC. It was only in the high 50’s here and 48 inside my garage. Well, a can of R134a at 48F doesn’t have much pressure, so I stuck a ½ used can in hot tap water and added it to the system. That works great, by the way.
Still, no AC. Car is parked in the sun, so I turned the heat to max and let the car run for a while. Interior got up to 85F, then I switched the ECC to max cool, recirc, with the fresh air off. The compressor clutch was cycling on/off every few seconds, so I know the pressure wasn’t high enough, besides, the return line from the evaporator was still warm. So I grabbed a full can of R134a, stuck it in hot water, and 10 seconds later, the compressor was no longer cycling and the return line was getting cold! Perfect! The temperature at the outlet was still only 52F.
I didn’t bother checking the pressure with a gauge…
At 5:15am the next day I started the car, backed out of the driveway, put it in drive, and rattle, rattle, rattle. I thought the heatshield fell on the rear driveshaft, but it was not speed related. I put the car in reverse and backed up to my driveway, popping the hood, and the noise went away? Not finding anything wrong, I put the car back in drive and drove to Columbus, about 12.5 hours. No noises, the AC worked just fine.
The next morning, I started the car to drive to the dorm, and there is a little noise at start up, but hardly as bad as the day before. After loading the car, a 4 hour process, we jammed ourselves in the car for a shorter trip to Chicago. When I put it in drive, my wife hears a “pop” and hiss and sees a cloud of white smoke. I stop and look under the car. A small puddle of what looks like antifreeze is on the ground, so I open the hood and see what appears to be green fluid all over the lower part of the engine, just behind the engine fan. I immediately think the lower radiator hose popped.
I drove ½ block to a small repair shop, and ask the mechanic to help me determine what it is. It looks like antifreeze, but is no longer leaking???? So I get directions to a Volvo dealer about 30 minutes away, armed with a bottle of premixed antifreeze.
The dealer, MAG Volvo on the northeast side of Columbus charged me $45 (1/2 hour) to tell me that the pressure valve on the high side of the AC blew, and what I saw was PAG oil and yellow dye. It covered everything from wheelwell to wheelwell! They cleaned it up and I was so relieved. The rest of the trip was totally boring :) .
Lesson learned, the hard way. I was just too lazy to check the pressure and I am happy the compressor still works. That was what was making all of the noise immediately after startup when the highside was over charged.
I guess it is time to bite the bullet and get the evaporator replaced. I just wish our dealer would charge $95/hour instead of $125/hour.

Klaus
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The 164 has a new home, all I am left with are a 95 854T and a 98 V70R :)

say there... i couldn't help but chuckle about the oily, yellow/green gook under the hood.

the A/C compressor in my 850 is cycling on/off every few seconds and i have a can or two of the newer 134a refrigerant in the basement. which port do you use to refill/recharge the system on the 850? i will take another look in my haynes and/or chilton manual tonight (it's my bedtime reading these days). i recall seeing one A/C port when i was snooping around under my hood one day... but where is the other one?

i seem to recall the writeup in the haynes manual didn't make it very clear.

the hot water on old spray cans is a good trick, eh?!!... been using it for years, my wife used to roll her eyes when when her hairspray would run out and i'd tell her to run it under hot water. but, her hair helmet would be locked in place for the day!

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-woodsytf '95 850 wagon 160k

There is only one port, the low pressure side. It is on the passenger side behind the headlight. The dust cover has 6Nm written on it, that means finger tight.

Shake the can real good before using. Just don't get it too hot!!

Klaus
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The 164 has a new home, all I am left with are a 95 854T and a 98 V70R :)

Quite a story Klaus. I hope you get it fixed up before the hot weather sets in. My '95 854T's A/C always worked great, and to my knowledge it was never serviced in 185K miles.

Good luck, Don
Former '95 854T owner, '05 2.5T V70 46K

My 1995 854T never has worked properly. Previous owner had a new compressor installed, twice, but not by dealer. I think it suffers the same disease that the V70 has...

Klaus
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The 164 has a new home, all I am left with are a 95 854T and a 98 V70R :)

Good story Klaus. Bad experience though,but its how the wise learn. at least thats what I tell myself; when I blame myself.

Best regards.
Howard. Isle of Skye.

'Anything can seem bad if you remember it'.
Homer Simpson.

Klaus,
Quite a story, she didn't leave you stranded though.
There is a high pressure switch in the system that is supposed to turn the compressor off if it gets too high.
where is the "high pressure valve?" There is no mention if it in any AC service information that I have.

From service info.
A/C PRESSURE SWITCHES
The A/C compressor is connected in series with the low pressure
switch, high-pressure switch, and safety switch. The high pressure
and safety switch cut power to the A/C compressor if pressure
in the A/C high-pressure circuit becomes excessive, supplying a signal
to ECM to start cooling fan.
The low-pressure switch (pressostat) turns A/C compressor on
and off to maintain pressure within limits.
--
Tom 69-1800S, 72-1800ES, 96-850T,2000-S70 GLT-SE

Rule 308 wrote this:


Yes, they sure as heck do and it is an eye opening experience when they blow. It is a valve on the back of the compressor, some of them are a simple blow off valve that will vent the entire charge and some of them are more of a poppet valve that will pop open and bleed enough gas out that pressures come back down.

R-134 tends to react to heat more than the old R12 stuff did so when an electric fan would take a dump the temps and pressures would spike ratherly quickly and it would blow the charge. When this happens and you happen to be under the hood, son of a gun does it grab your attention right now!

I missed your post on the overcharge, sounds like a funny one though.

Mark
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The 164 has a new home, all I am left with are a 95 854T and a 98 V70R :)

Tom,
You are correct. The service tech lied. Why am I surprised? At 4pm, this turkey drives into your shop on his return trip of 860 miles, the car is overloaded to the point that one more M&M will kill the Nivomats, a carrier on top that says Volvo on it, and 3 tired travelers.

I just pulled off the splash pan and the long hose that comes from the compressor to the driver's side of the condenser is very, very oily. Right where the hose connects to the metal line that continues to the compressor. I'll bet that is where the problem is.

I was planning to get the evap done this summer, so I guess I will beat the rush and get it done in a few weeks. New hoses too :) I wonder if I should spring for a new condenser, the bottom half looks like it was in a rock fight!

Klaus

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The 164 has a new home, all I am left with are a 95 854T and a 98 V70R :)

Interesting lesson, thanks for sharing. You are brave - I allocate all AC work to my mechanic. Oddly, my wife's 1999 V70 AC system has worked perfectly all these years.