I think this is what Klaus is referring to:



Does the following describe the scenario?.....

I assume that when you first get in the car and turn on the A/C, it works every time, at least for a while, then it starts to peter out even though the compressor is running. And even though the A/C is on, but not giving you cold air, when you turn the car off you get a fair amount of condensation draining under the car. So you ask yourself "How did it condense so much moisture if the A/C isn't working?"

When the airflow starts to diminish and turn warm, try turning off the A/C compressor button but leave the fan blowing. You may notice that when the performance starts to diminish that the airflow volume slows way down (restricted) and when you click the compressor off the airflow starts to increase again after about 30-60 seconds. Then when you click the the compressor back on it blows cold again for a while and then repeats the whole scenario.

I had this issue and what was happening was the evaporator was freezing up and restricting the airflow. The sensor in the is supposed shut off the compressor for a short period when it senses the evaporator is getting too cold. Then when the evaporator temp starts to rise a bit, the compressor will click back on. In my case the sensor was failing to click the compressor off so it ran and ran and ran until the evaporator froze up. A new sensor fixed everything right up.

On the V70 and S80 the sensor is poked into the evaporator plenum right up above the accelerator pedal and can be easily removed once the panel under the drivers side dash is dropped out. The sensor resistance can be checked both at room temp and after putting it in the freezer for a few minutes.

With my old sensor I was reading:

Garage Temp (80 deg?) = 1400 ohms
77 deg = 1500 ohms
65 deg = 1700 ohms
43 deg = 2200 ohms
Freezer Temp (28 deg?) = 2200 ohms

I'm told that a properly working sensor should read approximately:

3,000 ohms at 77 deg
10,000 ohms at freezing

Everything is inside the plenum except for the rectangular part on the end. That's where the wires connect.

You also want to make sure the evaporator drain is clear and not causing condensation to back up in the evaporator plenum.

Hope this help.....


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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)