Rear hvac module discontinued. Can mine be repaired?

[Stickle]

For now I manually set the actuator and unplugged it, all heat all the time. Once I get a replacement maybe I'll crack open the defective one and see what makes it tick (or fail to tick).

 

[Fless]

On my '04 Auto HVAC there are 6 calibrations (firmware) for the front and rear units, 3 each. All of the updated calibrations for these have been issued long ago, and a good scanner will tell you what calibrations exist in yours. Then you can check with your dealer or someone who can program modules to see if yours need to be updated.

Here are my calibrations (not part numbers) when I read them with my Tech 2, when I had it.

 

[Stickle]

On my '04 Auto HVAC there are 6 calibrations (firmware) for the front and rear units, 3 each. All of the updated calibrations for these have been issued long ago, and a good scanner will tell you what calibrations exist in yours. Then you can check with your dealer or someone who can program modules to see if yours need to be updated.

Here are my calibrations (not part numbers) when I read them with my Tech 2, when I had it.

View attachment 443208

I've come across a few mentions of calibration, lots that seem to say the mods are plug n play. Funny how a mass produced part like this can remain such a confounding variable after all this time.

 

[Fless]

I've come across a few mentions of calibration, lots that seem to say the mods are plug n play. Funny how a mass produced part like this can remain such a confounding variable after all this time.

The Dorman (and likely other aftermarket brand) modules will probably have the latest calibrations; they should be marketed as PnP if they are. GM hasn't issued new calibrations for these for years, so they're static at this point, and if the aftermarket mfr. uses them it'll be the latest. If you pull a module from the junkyard it may or may not have been updated.

 

[Rolexus]

Hey guys, so my hoe has the typical no rear heat issue due to the rear hvac module being bad. Dorman used to make a replacement however that seems to no longer be available. My question is, does anyone know how to repair my current one since this is a common issue? I figured maybe someone has done it or there is a way to do it, sort of like the lighting on the gauge cluster being able to be repaired by resoldering a connection in it. Thank you!

Nick

Had this same problem with my ‘05. Started 6 months “after” checking and replacing all blend door actuators (front and rear). After watching a YouTube video on testing this modulator, I actually called Dorman and got a similar answer.

Problem is with junk yards, this piece not that plentiful - “in good working order”. I bought 2 used (from junk yards) on separate occasions, only to see them fail within a few months.

So I decided to go a seasonal change over - in the spring I would set the blend door actuator back there to blow cold. In the fall I’d reverse to only blow hot. Once set, I’d disconnect any plugs to stop it from changing on its own.

Bit more work this way, not ideal, fairly easy job

 

[Doubeleive]

I could probably spend today and have a couple dozen of them in my hands, they are out there one in each vehicle unless it's been yanked already
there are 48 compatible vehicles in just 1 yard near me about 20 minutes away and 2/3 times more 1 hour from me.
that's just 1 yard.
that rear control module failing is really not all that common, it happens but not nearly as often as you guys are perceiving

 

[quicksilver8402]

Do not buy a Dorman rear climate control module! I bought one about 5yrs ago and it was hell. Every 3 days my battery was dead. After months and months of diag I put my gopro in the Tahoe (2 weeks straight in different places) and head the rear blower motor turning on. It would run for hours off and on. Through my work (18yrs as a UPS diesel mechanic) I met the Dorman rep. I told him about my issue and he said thousands of people had a problem with them. They were know to have a problem from a program issue. Just thought I would share that with you. I’m back in the same boat as you. I went to the junk yard and pulled one about 4 years ago and it went out a few months ago. I’m going to pull mine apart and see if I find any broken/cracked solder joints. Hopefully someone knows a fix on this as it’s been a problem since 2009. Gm even came out with a updated module and it didn’t fix anything.

I really wish someone would figure out a diag sheet for this board so that we can test it and figure out what's wrong with it and just replace a component. Or if there is a specific solder joint that's having an issue we can go straight to it and re-solder. Mine just failed on me and I'm going to go pull one from the junkyard but I opened the box everything looked good clean nothing visible no swollen capacitors everything looked fine but I don't know what everything's supposed to read so I can't just go in there blindly testing if someone had a build sheet on it and would tell us what commonly fails and what the values are supposed to be it would be great. It would also work great for that stupid Bose amp that I have under the console that needs to warm up before it starts to play. I would really love to be able to fix that because the Bose stereo works just fine for me I don't need to upgrade to anything else and have to change outdoor speakers and all that. I was really hoping someone on here would say hey it's this piece on this side of the board that usually burns out and if you replace it with part number blah blah blah everything starts working fine that would be awesome

 

[quicksilver8402]

I mean I really love my Yuke, but I'm getting tired of throwing used parts on it that are prone to failing. Where I can I get new stuff but some of these things there's no new parts for him and you just keep throwing something on that may fail next week it may fail next year and it may never fail we never know and I just hate having to go back into stuff that I've already fixed