2002 s60 A/C blows hot air

marshg2k · Post by **marshg2k** » 23 Jul 2014, 14:03

My car has a peculiar issue. I have explained the issue below as follows,

Problem:

1. The A/C will blow cold air for a while then suddenly stops and start blowing normal hot air.. it is like the compressor turns off.
2. If I turn of the A/C for a while about 5 - 10 minutes when I turn it on again it again starts to blow cold air as usual
3. This usually happens during the 100 degree summer weather., When I have to run the A/C in full blast.

Work done so far:

1. I have had the whole A/C system Flushed and the free on reloaded at the correct pressure.
2. I have had the thermostat replace3d.
3. Changed the clutch in the A/C compressor and had the compressor tested. Found to be working fine.
4. Had the whole condenser replaced.
5. Now my mechanic wants to replace the A/C Fan and/or the regulator. But if any of these is bad shouldn't the car be also overheating? The car is not overheating at all.

Observations:

1. When the A/C stops blowing cold air and starts blowing hot we tested the free on pressure and found it to be too high during this period. When we released some pressure the compressor kicks in and cold air is back. This seems to be consistent even though we made sure we put in enough pressure. I had this done at a Volvo certified dealer as well as by a mechanic I respect and the same continues to happen. The system seems to be adding too much pressure that causes the compressor to cut off.

Suspicions:

1. I suspect maybe there is some blockage causing this issue in the A/C system or maybe the A/C system is freezing up and blocks so when I turn off the A/C it thaws. But this does not explain the high pressure situation I mentioned above.

What do you think? Maybe my logic is flawed.

Post by **oragex** » 23 Jul 2014, 18:04

Make sure the radiator fan turns at high when the A/C is blowing hot air.

I read about someone having an issue with the A/C temp sensor, located somewhere inside the condenser box. It's accessible from near the pedals, at the bottom of the condenser box.

draser · Post by **draser** » 24 Jul 2014, 05:34

You pretty much have found the problem - freon overpressure and system shutdown. I would hope they replaced the receiver drier as well along with the condenser. It has a filter in it to remove the junk in the system. Can you find out how much freon they actually put in there, and then compare to how much the system takes? I know you had two techs working on this but you may need another opinion.

Post by **abscate** » 24 Jul 2014, 09:54

It does sound like blockage since you worked on the clutch and have eliminated clutch gap as a potential problem. The car will not overheat if the AC fan or regulator (?) fail.

Post by **chrism** » 24 Jul 2014, 14:19

Before you give any more money to anyone, pull the evaporator temp sensor out (5-10 minutes max) and check the resistance.

From what I've been told, a good sensor will read:
3000 ohms at 77 deg F
10,000 +/- at freezing

Mine was way out of whack at:
1500 ohms at 77
2200 ohms at freezing

It may still be that you have a blockage somewhere, but try the simple-and-free tests first. It seems to me that if the problem was truly a blockage, then the pressure would REALLY spike and the over-pressure switch would disengage the compressor. But it sounds like your compressor continues to run.

Question: When it stops blowing cold, have you tried shutting off the A/C compressor switch on the console and leave the fan running fairly high? If you do that, does the fan start to blow cool/cold air after about 30 seconds? And then does the cool air slowly become warm after about 30-90 seconds (at which time you can punch the A/C compressor button back on for another spell of cold air (for a while)?

otis44 · Post by **otis44** » 24 Jul 2014, 18:56

Our S60 exhibited the same symptoms last summer, I had the expansion valve in the firewall replaced and it fixed the issue. I don't remember if there was blockage in the valve or if it simply wouldn't open and close like it was supposed to, but the ac would work fine for a few minutes, then go hot, let the car sit and rinse and repeat. We have had no issues since. Good luck.

Post by **shiloh51933** » 28 Jul 2014, 08:04

Anytime u open the system condensation enters, making it mandatory to replace accumulator or receiver drier plus orifice tube. The silicates if exposed to air absorb the condensation but if exposed too long need to be change(accumulator/received drier).