1998 S70 GLT, earned my 100K badge two days ago. :) Happened to have my A/C freon flushed and recharged the same day, as it wasn't working. Blows ice cold now, but only for 15 minutes or so. The pattern seems to be that it stops working after the engine warms up for a while. Once it stops working, I can turn the A/C switch on and off, but it does no good...won't work again until I shut the car off and the engine cools off completely (hours, not minutes).

Here's the kicker. This afternoon, I drove the car around the city for about 45 minutes and experienced the same symptoms...no cold after about 30 minutes. Got home, and about an hour after I'd shut the car off, I walked by it in the garage and heard the air on inside the car. Car was off, key was out of the ignition, and the blower controls were set to "off"...and the blower was on, full-throttle.

Any ideas as to what might be going on here? Thanks to all in advance for your knowledge.

For what its worth. I have a 98 S70 here in Florida (its hot and humid all the time) and a similar problem is occuring. With mine, the a.c. will still blow after 15 minutes, but the air coming out is luke warm and humid (the a.c. vents on the dash get water condensation droplets)
If I turn it off for about 5- 10 minutes, it will usually blow cold again- for a while. Then I have to repeat the process.

Measure the gap between the clutch surfaces with a feeler gage. >.025 is too much.
--
Tom 69-1800S, 72-1800ES, 96-850T,2000-S70 GLT-SE

I think your problem is that the evaporator is icing up.
In high heat, high humidity conditions it is not unusual.
Try running it on low if you can fool the controls.
Or run the fan at a very low speed.
Can be cured by an A/C technician for big bucks.

-- S'V'

Prior post says that the heater/ac fan runs about 1 hour after shutdown to purge any water from the evaporator area. Perfectly normal.
As for the ac stopping while driving, if this is city/low speed driving on very hot days, mine does the same thing. The condenser can't cool fast enough. I am trying to find a solution.

Klaus
--
98 V70Rawd(108Kmi), 95 854T(88K mi), 75 164E(173K mi)

Thanks, Klaus. It's good to know the blower issue is normal. I was afraid the car was possessed (much more difficult to fix than freon or a switch). :)

I've learned that the problem doesn't seem to be tied directly to stop-and-go driving. What's unique about what I'm experiencing is the lack of a cold/hot/cold hot pattern; once it loses the cold, it's gone. The A/C only works after the car has been shut off for at least 8 hours...in the garage overnight.

It appears that some part involved in this equation is hypersensitive to heat. If I were to make an educated guess, I'd say there's a problem with either the A/C compressor clutch or one/both of the pressure switches. Thoughts? If so, does the system need to be emptied in order to replace the switches? And where are the pressure switches located? It would be nice to know what kind of a expense I'm looking at for this repair.

I have a 1998 S70 and live in South Florida. The a/c works continuously until the temperature rises above 90. Then the compressor turns off and on at intervals. My mechanic found power going to the compressor. He said the cost is about $800. According to my mechanic the original compressors had a problem with higher temperatures and would shut down. Any ideas will be appreciated.

Klaus,
Your problem sounds like the classic worn clutch problem. Measure the gap between the clutch surfaces. If it is greater than .030" you have found your problem. You can fix it by removing the clutch face plate and removing some of the shims to get the gap less than .020. (.015 works great) There is a procedure for removing the clutch face plate without discharging the AC. Tough but doable. I just did it to my step-daughters 94.
There is a lot of clutch theory involved here, but basicly when it get HOT (ambient temp > 85F) the clutch winding gets very hot during engagement. As it gets hotter the winding current decreases and the magnetic forces decrease to the to the point that there is not enough force to engage if the gap is too wide. If you turn off the AC with the switch for a while and let things cool down it will work again until it heats up.
Give it a shot.
--
Tom 69-1800S, 72-1800ES, 96-850T,2000-S70 GLT-SE

Any idea where I can find the procedure for removing the clutch face plate without discharging the AC. It appears I have the same classic worn clutch problem.

Thanks a lot..

Well, I won't say its the 100% fix, but I had exactly the same thing going on with my V70. The "official" fix was to replace the compressor/clutch although only the clutch was at fault. But regardless, it fixed the problem.

Ideally, if you need to stay clear of a dealer the right answer is to do the adjustment to the clutch as suggested here or if need be replace only the clutch assembly. This situation appears to be a case where going to an A/C guy might be a better and cheaper option than going to the dealer. Volvo, amongst other Euro OEMs, want crazy money for a compressor when in fact you might be able to do way better by having an A/C guy figure out that a Volvo compressor is the same as some other OEM. A buddy of mine with a BMW went to the dealer to get his A/C fixed for the same kind of problem. They quoted him over $1000 for the compressor/clutch. He went to the A/C guy who knew enough to see that the assembly was the same as a Chrysler and charged him around $250 for the same thing.