Newbie with ongoing HVAC weirdness. Any ideas? - SOLVED

[Fless]

Also, Dr. Shock has some videos on using the Tech 2 for updating calibrations. I'm not going to go into the difference between using the offline TIS2000 that typically comes with the Tech 2, and using online SPS. That depends on your programming hardware setup. I did all mine using TIS2000 since those calibrations are no longer being updated.

Later in the video (around 7:15) you can see the updated calibration description, where it lists what issues that particular calibration will correct.

 

[mtglick]

Your seat issue may be a problem with the BCM or the DSM, not the PCM. There are multiple calibrations for the various modules and sub-systems. Here are a few of the calibrations that I verified and updated on my '04 (L59 engine):

View attachment 456953

@Fless , that's very interesting. Thanks much for this, would get my vote for a tech sticky (if you folks do that kind of thing here). What's really got my attention are those last three entries--ultimately, that's kind of what I was asking about. If there are custom selections for HVAC calibrations, and they corrupt or get out of alignment, could explain some of the ongoing issues related to how the whole system functions (or doesn't). Will research that further.

 

[Fless]

Here are a couple of threads that might interest you:

This is a listing of some of the Tech 2 owners; many are willing to help local folks that don't have one:

Tech 2 Owners Map

There are quite a few members that have a Tech 2 and there are always people who wish they had one to use so I thought I would post this thread to try and help each other out. If you own a Tech 2 and would be willing to help out another forum member that might be local to you then post up your...

www.tahoeyukonforum.com

The Case for the Tech-2

The Case for the Tech-2 By J. A. Burns, Port Saint Lucie, Florida I first learned the complete necessity of owning a scan tool designed for my given car at the dawn of the computerized automobile, owning and racing a stable of turbocharged Buick Regals. Even only being able to see and work...

www.tahoeyukonforum.com

 

[mtglick]

As to the original issue, I got it fixed this AM, and (spoiler) it wasn't the resistor.

When I pulled the hush panel down, everything looked good, so I left the first resistor in place and just plugged in the new one. No change. Pulled the original resistor, looked at the connections, nada. I had the system powered up and as I was moving wiring around to get the new resistor out of the way, the fan started up. Turned everything off, looked at everything, nothing looked odd, system was now working normally.

I was just on the verge of declaring a gremlin in the first resistor when, for whatever reason, I decided to pull the fan. To be honest, I don't love putting the fans back in, for whatever reason what SHOULD be a quick thing almost always turns into a fight for me, so I hesitated, but figured it would bug me down the road if I didn't check it. Popped the fan out, looked at it, was fine, and as I went to put it back in the mount, I disconnected the fan.

Which was where the problem was.

The vehicle-side fan connector had melted INSIDE the plug. The exterior looked fine, no discoloration or anything that looked off, but it was distorted just enough to create a small arc, which continued to grow as the system pulled more amps over the connection. More arc, more heat, more distortion, until it eventually broke the connection. When I bumped the wire, it moved just enough to re-establish the connection, temporarily resolving the problem. If I hadn't pulled the fan and looked at the interior of the plug, could have been much worse down the road.

The new resistor came with a new pigtail, so I spliced the new connector into the harness, cleaned the pins, plugged everything back in, et voila. Working fan. I let it run for about ten minutes, checked it again, nothing changed, amp draw looked OK, so declaring this one done, at least for now.

Thanks y'all for the assist, moving on to calibrations research.