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AR15.COM
5/27/2010 5:34:22 PM EDT
My '03 Duramax has developed an A/C issue.

I pulled the DTC and it is a U0164 Lost Communication with HVAC Control Module.
When I first start it, if the A/C is on, it will engage the compressor (I can hear it load the engine) for one cycle, and then it goes warm.
I pulled the fuse for the controller while the truck was running, and it gave me A/C back while it was running, but as soon as I turned it off, it was up to it's little tricks again.

Any ideas? The diesel forum has been less than helpful.
5/27/2010 6:41:02 PM EDT
[#1]
HVAC control module went bad?
5/28/2010 4:07:17 PM EDT
[#2]
sounds like the temp. actuator  motor went bad and is defaulting to full hot .
5/29/2010 6:50:19 AM EDT
[#3]
It's not hot like I turned the heat on, it's warm, like the vent.

I think the Controller in the dash is fried.