Air conditioning seemed to work when we got the car but I never measured temperatures or checked refrigerant pressure. Noticed the refrigerant lines frosted up everywhere when it was running:
Also noticed that the AC compressor was short-cycling (clutch engages/disengages frequently). Both of these indicators are symptoms of low refrigerant charge.
Using a thermometer in the center vent on max AC, I measured 52 degrees for a feeble 18deg split (70 outside), which is the difference between outside air temp and the cooled air coming into the cabin. On most cars you can expect 30-40deg of cooling (split).
Connected pressure gauge to low side refrigerant port and measured nearly no pressure on the suction side of the compressor. Should be 30-40psi. This car is unusual in that it has no high side pressure port to monitor compressor output.
Added two 12oz cans of R-134a refrigerant through the gauge set and got the low side pressure up to 40psi where it belongs.
Vent temperature is now a cool 42 degrees at 82 ambient which is a 40deg split. That’s at idle.
While driving the car around, it can go below 40deg with the compressor running faster and air flowing through the condenser.
The compressor no longer short cycles and the refrigerant lines sweat but do not frost up now.
Noticed fluorescent yellow leak detect dye at the low pressure port so somebody was looking for a leak sometime back. With such low pressures obviously there is a leak, which is no surprise on a 15 year-old car. If it’s a small leak, I can just refill with refrigerant periodically. If it discharges quickly, I’ll have to go hunting. Most likely a compressor shaft seal in that case. Will keep an eye on A/C performance this summer.
2x $12 cans of R-134a
1997 Volvo 850 Wagon Project 