I purchased a used 2004 Corolla this winter, and the past couple of days I finally turned on the AC and it didn’t work. It blows hot air…hotter than the air that I get if I just use the fan with the AC off.
I went to the auto store and got a can of R134a with a gauge attached. I did what it said (ran the AC on max for 3-5 minutes,) and when I attached the gauge to the low-side port, the gauge read over 100 PSI. The “optimal” PSI according to the instructions on the can for the ambient air temp is 50-55 max. So…what gives? If I was low on R134a, wouldn’t that cause the pressure to be low? And if there is too much in the system, how did that happen, and what can I do about it? Can I just “bleed” off the excess somehow?
The compressor isn’t pumping. Is the drive clutch engaged? If the compressor shaft is indeed turning then the compressor is broken. If the clutch isn’t engaged then there is some electrical reason the clutch solenoid isn’t energizing.
I gather (and hope) you did not add the refrigerant. Adding it when’s it not needed is one way to get too much into the system.
Normal rest pressure (system off) is around 100 psi. Normal operating pressures are typically 30-35 low side, 150-250 high side. Knowing just the low side reading doesn’t tell us much, but with some more info we might be able to get some idea what’s going on.
First, it’s critical to know if the compressor is operating or not. CRITICAL. If we don’t know this, we don’t know squat.
At the front of the compressor, the pulley spins around the front plate of the compressor clutch when the A/C is off. You can see that the clutch is not rotating when the engine is off, and when the engine is running but the A/C is off. When the A/C is turned on, there is typically a loudish clunk when the clutch engages, and the clutch can be seen to spin.*
If the clutch is not spinning, there’s an electrical problem preventing the A/C from even trying to operate. This needs to be found and fixed before anything else can be evaluated.**
If the clutch is spinning, it would be really helpful to know the high side pressure. There could be a shot compressor, a faulty expansion valve, or some other problem.
*Clutch and pulley assembly in these pictures: gold, black, black. Disassembled clutch showing, left to right, field coil, pulley & bearing, front plate.
**But first make sure the clutch can be rotated. If not, the compressor is seized.
