Hey everyone ~

I took my S80 2.9 to get an a/c service. Previously I had tried to add/take out R134 to make the air in the cabin cooler. Only being able to add on the low side, I was certain I could not get an accurate amount in the system. After a few days with experimenting with R134 amounts, the compressor clutch started to engage and disengage every 15 seconds after the car a/c had been on for about 5 minutes (when the pressure had built up maybe). When disengaged, the air is cold, but it rises by about 5 degrees with a little humidity until it kicks in again. I gave up, so I took it to a local mechanic who evacuated the system, air, and oil. He said there was 2.8lbs of refrigerant in the system, and it should only have 2.17lbs. I was starting to freak out until he told me that I couldn't overfill the system because of high and low pressure sensors that were a part of the system. He refilled everything, and I drove away with pretty cold a/c. However, the compressor still cycles on and off every 15 seconds. I took it back, and he said that it should work itself out in a day or two, when the computer is used to the amounts of refrigerant. This seemed unlikely to me. Is there something else it could be? Did I ruin something overcharging it. It's bearable in the 95 degree heat, but I don't want the compressor or clutch to wear out because of incessant cycling.

Volvo for life so far

 

54 people have viewed this, and nobody is a pro?

 

He is right... the compressor is doing its job correctly!

The only time a compressor should ever be overfilled is when the rings are wearing out in it and you want the cooling. It raises head pressure a little but usually works. Yes, I am HVAC certified!

 

The compressor will disengage when the evaporator temp drops to 6C (about 42F) How's your cabin filter? dirty filter -> reduced airflow -> compressor cycles so the evaporator doesn't become a block of ice.