Low suction pressure freezing up evap on Volvo S80

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Low suction pressure freezing up evap on Volvo S80

Postby Swedal » Mon Aug 21, 2017 8:15 am

Trying to figure out why this Volvo S80 2003 never cuts out the AC compressor and why it has such a low suction pressure. AC works fine and cools very well but freezes up completley. I have evacuated and filled the system with 1000g R134a as label says. I suspected the evap temp sensor and removed it and did some meassurements and it seems to react as a thermistor. Maybe the ohm values are off? Well after some minutes of driving I have 17F (-8C) from the vents and ice is building up. Compressor never shuts off.

Question #1 Why the heck is suction pressure that low to even get such low temps from the vents?? I have never seen evap temps that low in a car.

#2 Why does the compressor not cycling on and off? Can I be sure it has to do with the evap temp sensor? I mean even if suction pressure is too low I would still have cut off from the compressor when evap temp is too low, right?

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