Keeping cold

[S1nemesis1s]

I just noticed that the rear heat is not working in my 04 Tahoe Z71. When I replaced all the hoses and water pump and thermostat I had to burp the system, then drive it around a while and it started coming out hot. I have add some antifreeze here and there when I noticed it was a little below fill line.

I just had the transmission cooler lines replaced earlier this week and I just noticed the rear heat is not working! Could this have caused the problem?

The air blows out but it is cold, not hot. What am I looking at here? I have read other threads but I am getting very confused. Is this a simple fix or is it a pain? I would love to have some rear heat again. ANy help guys would be most appreciated!

 

[S1nemesis1s]

I went out and checked the rear heater hoses, both are hot - the ones under the tailpipe at the rear, so I am getting heat. I read that the issue is common and can be part 15832319, ACDelco 15-73506 GM Original Equipment Air Conditioning Control Module. So I ordered one of these. Hopefully this will fix it. I appreciate any suggestions!


https://www.amazon.com/gp/product/B000S2SHZK/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

 

[S1nemesis1s]

Here is where it gets weird - I just pulled the fuse for it, 10A HVAC/ECAS did the reset procedure and the heat worked!!!!! WTF! So...umm...I guess I wait and see if it continues to work? Or should I replace that unit just in case? I did the big three about a week ago and maybe that wonked it out. I know that doing the reset totally reset my climate control. This is plain weird....

 

[iamdub]

How long do you have until you can return the module you just ordered? Maybe don't cancel the order and hang on to it for a while to see if it stays working. Considering the recent electrical work done, it may have just needed that reset. After all, they are small, non-powerful and fairly sensitive computers in these modules that could be easily scrambled by a few short power cycles in rapid succession.

 

[S1nemesis1s]

I am thinking this might be the case. It is fulfilled by Amazon so I have a a while before I have to return it. I think I will hold onto it just in case, I may install in and just call it day as well - when it warms up outside that is. Weird for sure. No wonder the truck has seemed so cold Ha! I just hope this holds...wish there was a reset for the power mirrors...they are all over the place.

 

[HiHoeSilver]

Here is where it gets weird - I just pulled the fuse for it, 10A HVAC/ECAS did the reset procedure and the heat worked!!!!! WTF! So...umm...I guess I wait and see if it continues to work? Or should I replace that unit just in case? I did the big three about a week ago and maybe that wonked it out. I know that doing the reset totally reset my climate control. This is plain weird....

What's the procedure?

 

[S1nemesis1s]

What's the procedure?

For me I watched a couple of YouTube videos and winged it. I pulled the fuse, started the truck ran it for 1 minutes. Turned it off. Let it set for a few minutes, then turned the key to the "on" position but no further for 30 seconds, then turned it off, waited 30 seconds, put the fuse in and started the truck. The auto climate control was reset to factory settings, like 74 degrees or something and I HAD REAR HEAT!

I think this is how you are supposed to do it: "Pull the fuse under the hood, turn the key to the "on" position but no further, for 30 seconds, then turn it off, wait 30 seconds, put the fuse in and start the truck."

 

[Tonyrodz]

For me I watched a couple of YouTube videos and winged it. I pulled the fuse, started the truck ran it for 1 minutes. Turned it off. Let it set for a few minutes, then turned the key to the "on" position but no further for 30 seconds, then turned it off, waited 30 seconds, put the fuse in and started the truck. The auto climate control was reset to factory settings, like 74 degrees or something and I HAD REAR HEAT!

I think this is how you are supposed to do it: "Pull the fuse under the hood, turn the key to the "on" position but no further, for 30 seconds, then turn it off, wait 30 seconds, put the fuse in and start the truck."

Is that only for the electronic hvac? Without the dual sliding switches?

 

[HiHoeSilver]

For me I watched a couple of YouTube videos and winged it. I pulled the fuse, started the truck ran it for 1 minutes. Turned it off. Let it set for a few minutes, then turned the key to the "on" position but no further for 30 seconds, then turned it off, waited 30 seconds, put the fuse in and started the truck. The auto climate control was reset to factory settings, like 74 degrees or something and I HAD REAR HEAT!

I think this is how you are supposed to do it: "Pull the fuse under the hood, turn the key to the "on" position but no further, for 30 seconds, then turn it off, wait 30 seconds, put the fuse in and start the truck."

I'm gonna have to try this. Mines 06 with digital hvac. I, too, have no rear heat. Just blows cold. I assumed actuator, but its pretty expensive.

 

[S1nemesis1s]

Is that only for the electronic hvac? Without the dual sliding switches?

Not sure, might is the digital one, but, if its the same fuse, it may work - works on the same principle I would think.