It's my 05 1500HD that has the digital climate control head unit. My a/c compressor will not run with the either the defrost or the a/c button depressed. The a/c symbol on the display just flashes.

I tried a couple things thus far. I jumpered the low pressure switch with no change. I checked all a/c related fuses and they were all good. I forced the a/c clutch on via EFILive and the compressor does run.

There is a BO229 code for the recirc door but it's been there forever and the a/c has worked with it coming in. It will not clear, I have done the relearn multiple times meaning I need a new motor eventually. I cannot seemingly find a simple a/c clutch request PID on my software which would be helpful here.

It was working fine, I disconnected the low pressure switch and reconnected it ( not noting whether that affected anything) and then noticed it hasn't been working lately.

Any ideas?

 

If I have a code, that is generally the first place I start however a couple of other things to look at:

I had a bad connector for the a/c refrigerant pressure sensor (the one on the high pressure hose at the compressor). I cut in a new one and problem solved in my case. There are three wires that tie to the PCM, gray for 5 volt, black for reference ground, and then signal red/black. I found my problem with ohm meter between connector and pcm pins. You may want to verify your wires and connector similarly.

Second since you said it was working before you pulled the connector, you may want to check the low pressure switch (near the dryer) connector. The black wire should be a good ground and the dark blue wire is signal that goes back to HVAC module.

I am assuming that the system has sufficient refrigerant verified with gauges.

You were able to verify that the compressor will work with EFI Live therefore the problem must be signal for a legitimate reason, defective signal reason (broken connection, defective sensor, etc.) , or defective processor of the signal (HVAC module, PCM).

Good luck

 

The code is, well not something I want to repair. It's of course the blend door motor that requires most of the trucks dash to come apart to get too. And like I said it was working with the code present anyhow. But I want that fixed so I will see how much it going to cost me as I don't want to be bothered doing it.

I didn't look at the high pressure switches connector and that could be something. The low pressure connector could be the issue but it's not the switch as the jumper would have allowed the compressor to start if that was the case, and it didn't.

The system has adequate charge to run so no problem there.

I am wondering honestly if it's not the Hvac module itself. I will keep mucking around with it and see what I come up with.