A/C comes on ice cold, then after 30 minutes or so of driving the A/C starts blowing warm air. Turned off the A/C for 5 minutes or so then turned it back on. A/C is blowing ice cold again until we reached our destination. This happened a couple of different times.

This is for my 1998 S70 with around 160k miles.

The evaporator, accumulator, etc. has been replaced a few years back, and I don't hear the compressor clicking off and on, which is usually the case when it's low on freon.

Any thoughts?

Thanks in advance!

-Brian
1998 S70 GLT ~ 175k miles
1998 S70 GT ~ 160k miles
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Brian M. - 1998 S70GLT, 1998 S70 GTA

Could it be electrical or the electronics?

After driving the S70 a few times I noticed that it happens randomly. So I'm driving down the road for an hour with the A/C blowing ice cold and then it starts blowing warm air. I shut the A/C and fan off for just 2 minutes and turn it back on, and it starts blowing cold again. It's random which means it could happen again in 15 minutes or not at all. I drove the car last Saturday for 5.5 hours and I had to turn off the A/C and fan twice.

Any thoughts?

P.S. I tried putting more freon but the gauge already showed full.
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Brian M. - 1998 S70GLT, 1998 S70 GTA

It could be the clutch gap on the compressor is getting too large. Easy enough to measure and should be less than .040, around 0.20 is ideal. When gap gets to .040 it may require too much electricity to pull on the clutch.

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Keeping it running is better than buying new

Your car does not have a temp sensor in the evaporator like the newer models.

I hope you don't move the temp switch to max cold every time you start the car. Try keeping it at a reasonable temperature setting and let the ECC regulate the temperature. It is possible that you have too much R134a in the system... The gas expands when hot.
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Keeping it running is better than buying new

“....Your car does not have a temp sensor in the evaporator like the newer models.....”

Interesting. So is it the cabin temp sensor that tells the compressor when to cycle off? (Something has to tell it to cycle on/off/on/off so that the evaporator doesn’t freeze up.) If it’s the cabin temp sensor that governs the compressor then good call to not run it for long on max cold. A good de-linting of the sensor may a good idea. It could have 20 years worth of build/up in there.
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Current rides: 2005 Volvo S80 2.5T, 2003 Volvo V70 2.4NA, 1973 Volvo 1800ES (getting ever closer to road worthiness)

The belly button lint in the sensor does need to be cleaned occasionally, when it gets bad enough, the blinking lights of death will flash 20 times to let you know that something is wrong. A vacuum with a crevasse nozzle works pretty good.

I have never had a problem with icing, mostly because I never change the temp settings. If the car is hot, the blower will run full blast. If the car and engine is cold, the blower will slowly start when the coolant temp increases.

I just wish the older models had better systems to remove the water after the engine is turned off. My 95 needs a new evaporator core...
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Keeping it running is better than buying new

My 2003 V70 was doing that when the evaporator temp sensor failed, causing the compressor to run and run and run until the evaporator froze up. So I would have to shut it off for a few minutes to let it thaw out. Then I could turn it back on and repeat the whole cycle. If your compressor wants to run continually and not cycle off every so often then you may have the same problem.
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Current rides: 2005 Volvo S80 2.5T, 2003 Volvo V70 2.4NA, 1973 Volvo 1800ES (getting ever closer to road worthiness)