Intermittent A/C

Greetings everybody,

My girlfriend had some work done with her 1998 Pontiac Sunfire’s A/C system and since then it has become intermittent. It’s been like this for a while as she doesn’t have anyone look at it since she thinks it’ll be expensive.

Once the car runs for a while the A/C will work fine, however, after driving it and then getting back in it will not work anymore, the clutch doesn’t engage. If the car sits for a while longer, not sure how long, the A/C will work fine again when getting back into the vehicle.

The relay to the compressor works okay, and the engine will always rev up when the a/c system is turned on, however, I’m curious if the low pressure switch is possibly the culprit. I think the location is on the passenger front side of the engine compartment near the headlight. I’ve heard this is a bad place for it as the wires always get messed up, especially during maintenance, also I’ve heard that it could be the PCM or ECM. For the pressure switch I am wanting to use a fused jumper to see if it could be the pressure switch, or by tapping on it to see if the compressor turns engages.

Any input from the crowd?

Start by checking to see if the wires to the switch are in good shape. If not, repair them.

If you bypass the low pressure switch, only do so for a few seconds, or you risk damage. If your bypass test works, replace the low pressure switch. If it still cuts out like before, your low pressure switch was good and doing it’s job. The real problem then would be low refrigerant level.