After changing my second bad delco battery recently, the auto climate control seems to have gone crazy... It seems to run in all the modes and switch air flow directions fine, but no matter what temp setting I use the outcoming air temp swings from hot to cold and back again. I read some other posts about this, but no one seemed to have any answers or solutions that they found. I have had this happen before after some work was done (again a battery disconnect was involved) but it went away after 15-20 minutes of driving (as I think back on it). I don't know that I did anything to solve the issue... it may have solved itself.

I doubt it's related, but I also have a problem with the 4WD... the TCCM doesn't click (self check) like it should at start-up. So it will not choose a mode (2WD , 4 Auto, 4Hi, or 4Lo) and all lights on the selector switch go blank. I had someone look at it (they replaced the selector switch, but it didn't help). The TCCM seems fine (visual), but I have no idea how to truly test it. After the last battery problem, the TCCM worked a few times and it was in 2WD. I got it to switch to 4 Auto, but no other modes could be selected. After choosing 4 Lo, it tried for a minute then popped the service 4WD light. That light is normally on all the time when the TCCM doesn't pass self check at start-up. The actuator motor in the Transfer case is supposed to be good according to the mechanic and it moves freely.

Any help would be appreciated. Thank you!

 

Welcome to the forum

For your a/c, it probably needs the actuators recalibrated.
with the ignition off, Remove the RDO BATT fuse for 10 seconds and then reinstall the fuse.
Place the ignition switch in the RUN position and wait 40 seconds for the ECC module to initialize

Calibration of the electronic climate control (ECC) module occurs whenever B+ is removed and then restored to the ECC module. During this calibration process the ECC module will automatically command the temperature door to the full HEAT position and then to full COLD position. The ECC module records both the minimum and maximum door positions and uses this data, which is in counts, to determine temperature door settings based on customer selected temperature settings

As for your 4WD, It sounds like a faulty transfer case shift control module.
I don't know how your mechanic figures that the encoder motor (actuator) is working properly, but if it is and the switch has been replaced, the TCCM is the only other possibility...as long as the wiring is ok.
I don't know how this could be tested without a scanner.

Post again if you find any answers, or if this info helps. Good luck.

 

Okay I ran the Re-calibration of the ECC... It didn't seem to change anything (the temp door seemed to keep switching back and forth after many minutes of trying). Then on my way to work (just over 5 minutes of driving) it occurred to me that maybe it had to be set to full auto in order to calibrate. It quit moving the Temp door within a minute of switching to full auto. Coincidence that it just gave up about then or was my thinking right? I may try to simulate the issue by pulling the RDO Batt fuse again, but why screw-up a good thing since it's working now ;-).

 

4WD issue was the TCCM... Now I'm on my third Delco battery and the ECC is cycling again [:@]. Back to the drawing board!

 

[:@]A week ago, I had to replace a battery, gone dead. While Jumping (and failing) with the original battery I had noticed strange "surge" noises coming from the dashboard, but didn't think too much about it, since the starter solenoid was also just "clicking" with the dead battery. Anyway, after replacing the battery, my Computer Controlled Climate Control is also just cycling back and forth between hot and cold - and various lower and dashboard vents in between. I've tried the RDO BATT fuse removal several times today and am not having any change in its behavior.

Anyone know of any other "reset" mechanisms? I'm beginning to long for a truck with no automatic,power, or computer controlledanything []

Thx,
CJ