AC Light won’t turn on

[TheCodester]

My problem is intermittent. One day the AC light will turn on and cool perfectly. The next day it won’t come on when I press the AC button. Blows super hot air.

Replaced AC relay, AC control unit, bypassed pressure switch. I can’t figure out what it is.

At this point it’s got to either be Freon or the compressor. About to just take it to the shop.

 

[Ilikemy3s]

I was thinking the pressure switch but you already did that .... ??

 

[Maverick6587]

I see you bypassed the pressure switch but, did you get a read on the pressure of the high and low side of the system?

Did you verify voltage on the bypass when the AC is on?

Could be a stuck pulley, although I'm not sure if that would stop the light from turning on. I would see if maybe the pulley is stuck. Watch the video below if you are unfamiliar with this process, It's in the very first minute of the video.

Be very careful when attempting to get the pulley to turn! You don't need to lose an eye or an arm. I would probably try and just softly tap it with a small hammer first.

 

[budwich]

As suggested, get a reading of high side and low side pressure. In general, the AC pressures can be read using torque and the proper pid. It is likely that the pressure sensor reading is causing the control unit to activate. The pressure sensor can't be readily bypassed (not talking about the low pressure switch which is different). However the pressure sensor can be check to see if it is working and has proper voltage / resistance readings.

 

[16vcabman]

Check the refrigerant pressure. A set of gauges will tell you what your charge is. I have found a lot of cars overcharged by owners using cheap over the counter quick charge kits.

 

[Mooseman]

Could be the high pressure sensor. IIRC another member had a similar issue and the sensor was defective.