I have a 2003 Volvo S60. My A/C blows warm air after driving 10-15 min. I turn off for about 2 mins and it blows cold again. It use to blow warm air at complete stop if sitting more than 5 min. Now it blows warm when driving. No noises, no messages on dash, nothing turns off. Temp of car stays same. All normal run. Its just the a/c problem.

SOURCE: heater starts to heat then afer a minute blow cold

water pump

SOURCE: After approx 40 min of highway driving the AC stops blowing cold

This is a problem solved by moderation. There are pressure switches in the system which cut off the compressor for too high a charge and too low a charge. The unit is suppose to cycle between a predetermined range, a moderation between high and low. If you were having problems before replacing the freon there is at least 1 pressure switch that could have been your problem in the beginning. If you have a manifold guage which shows high and low pressure you can tell when the pressure switch is open or closed. Some switches and for sure the autoparts store selling them can tell you the op[erating range of your switch. You can try just replacing the low pressure switch and fly blind without the manifold guages. Know how many ounces of Freon you put in? Compare to specs to see if you overcharged.

Marvin

• 85242 Answers
• Posted on Jun 09, 2009

SOURCE: my ac blows cold air for the first 5-7 min then

have the low side pressure cycling switch tested.

SOURCE: My 94' 940 volvo AC is not cooling.

if the line to the condenser ices back at that point, the system either has too much freon in it or not enough. its 134a refrigerant. if you add freon when its really hot outside, the pressures will be a little higher than normal. do not overcharge the system, since freon really doesn't go bad, it can get contaminated with moisture, and degrade the system. you need to have it dumped out and pulled into a vaccuum and see if it holds 30 inches of vaccuum. vaccuum boils out moisture in the system. check the drier/accumulator at the same time. if it has a sightglass on it , it will change color if there is moisture in the system.

SOURCE: heater blows cold air ,at idle and blower motor

the heater control valve is not opening all the way.
look under the hood on one on the heater hoses .
you should find a vaccum controled heater hose valve.
make sure your not low on coolant also.
also make sure none of the heater hoses are pinched off.