AC failure diag help

[andrewwynn]

Check continuity of the pressure switch while it's unplugged I believe It should be a short.

As to "where does it say" and aux fan required for AC: xoutpost it's the #1 diagnostic mentioned at the beginning of summer when people start to realize their AC not working.

The test I described (watch for the fan self test at start) will let you know the fan is working.

My advice: spend the $ you would ha e on a pro to measure your refrigerant level and buy a foxwell. You'd be able to both contirm status of the low and high pressure cut outs and engage the aux fan and compressor.

I've never had to do the unplug the low pressure sensor test but I didn't remember my fan running constantly for the first two weeks I had my X5 until I realized the low pressure sensor was unplugged so I was surprised to hear that's the usual test method.

So for now and without additional tools that is what you have to work with.

Unplug the low pressure sensor, car running and I'm not sure is ac switch needs to be on, the aux fan is said to kick on immediately if you do this, it's the method commonly used to test the aux fan and I've read often that if the aux fan isn't running the AC will not engage.

The theory is the condenser needs airflow and can't rely on the clutch driven fan when not moving. I have noticed that when I'm stopped and it's warm, if I block the clutch fan the aux fan will kick on in mere seconds so it's very sensitive to temp and kicks in at a much lower temp program when AC is engaged.