Duramax HVAC..... I'm stumped

Clark · Dec 28, 2011

OK, I put in some new batteries and now the HVAC is wigging out. I'm not sure weather it's related or not.

I have a 2007 Classic Silverado, with Manual HVAC controls. The backlights come on, and i can control fan speed, that is all.

It's stuck blowing on your face only, drivers side is max hot, passenger is max cold. I cannot change to blow at your feet, or defrost, i cannot change the temperature, i cannot use the AC, cannot use recirculate, cannot turn on rear defrost.

I checked all the fuses under the dash and under the hood, nothing is blown. I reflashed the ECU and checked for DTC's with EFI live.

I cannot defrost my windshield, my face is dried out, and my passengers are freezing.

I tried searching the duramax forums and came up empty, i'm hoping someone on here might know something. OR might get me pointed in the right direction on where to start looking. I don't want to start throwing parts at it.

Thanks,
Clark

crash2 · Dec 28, 2011

I know nothing :haha:

crash2 · Dec 28, 2011

Start by pulling the cluster bezel and then the head itself(bezel clipped in and head 7mm screws). Disconnect it for 10-15 seconds and reconnect it and see what happens. More than likely it was on the edge of failing and pulling battery voltage was enough to spike it (had a BCM do that recently). If that does nothing your head is dead.

KarlVP · Dec 28, 2011

Just for shits and grins did you try pulling all the fuses (even underhood) starting the truck, shutting it off and then re-installing the fuses?

This worked when my rear seat DVD system went all wacky on me.

Also helped get another buddies "service 4wd" to stop displaying.

Clark · Dec 28, 2011

i will try both of your suggestions, thanks:awesomework::beer:

xjoffroad · Dec 28, 2011

Check the suburban forums. Common issue and I had it happen in my 06 suburban. I remember exacting with I did to reset it but it worked.

johny5 · Dec 28, 2011

so to hijack this thread . is there any know issues with the gas gauge in the 05 duramax.

oh and also the heated seats , the switch flickers but no heat

xjoffroad · Dec 28, 2011

johny5 said:
so to hijack this thread . is there any know issues with the gas gauge in the 05 duramax.

oh and also the heated seats , the switch flickers but no heat

The gauges are known to have issues. My 06 had to have the whole clutter rebuilt. All my gauges died. Had something to do with diodes or something like that. Have crash check your vin# there's a recall on them.

Clark · Dec 28, 2011

I tried resetting the HVAC by both pulling the fuses and unplugging the control unit. Niether method worked.

My gauges are good though:beer::redneck:

I also tried this method:
http://www.duramaxforum.com/forum/diy-tech-discussion/9854-fixed-dual-climate-control.html

crash2 · Dec 28, 2011

johny5 said:
so to hijack this thread . is there any know issues with the gas gauge in the 05 duramax.

oh and also the heated seats , the switch flickers but no heat

There is a problem with the clusters.

One of your heating elements is bad.

crash2 · Dec 28, 2011

xjoffroad said:
The gauges are known to have issues. My 06 had to have the whole clutter rebuilt. All my gauges died. Had something to do with diodes or something like that. Have crash check your vin# there's a recall on them.

Not a recall but a special policy.

crash2 · Dec 28, 2011

Clark said:
I tried resetting the HVAC by both pulling the fuses and unplugging the control unit. Niether method worked.

My gauges are good though:beer::redneck:

I also tried this method:
http://www.duramaxforum.com/forum/diy-tech-discussion/9854-fixed-dual-climate-control.html

If you disc. the head and plugged it back in--might as well stop there and replace the unit. (thats just an educated guess).

Zoediak · Dec 28, 2011

my experience with these recently had the same thing happen.

what my research showed was that the actuator for the controls is stuck in one position...

do a search for heater actuator control problems....

i know that there are some certain steps to 'reset' them, if they don't reset, then they usually need to be replaced.

if you have the dual climate control like my classic 2007 silverado, then you have seperate actuators for each side.

here.. i just did a quick search... try this:

linky1

and here is another article on this....

linky2

both articles mention a code that was thrown... put on a scan tool and see if there is one by chance...

just another thing to try...

Zoediak · Dec 28, 2011

oh yeah.. forgot to mention... all the problems that i had with this were AFTER full battery disconnect as well.

when you reconnect the battery it tries to do a reset of the actuators, and depending on where the controls are positioned (read the article) it is important step!!! will either allow the actuator to "reset" or it will cause it to fault and act all retarded...

I was able to reset mine to where they work properly again so i didn't have to fork out the $46+ each for new ones...

read through the article in the first link fully and try the 'resetting' procedure near the end of the article..

hope all this mumbo-jumbo helps out....

crash2 · Dec 28, 2011

Zoediak said:
my experience with these recently had the same thing happen.

what my research showed was that the actuator for the controls is stuck in one position...

do a search for heater actuator control problems....

i know that there are some certain steps to 'reset' them, if they don't reset, then they usually need to be replaced.

if you have the dual climate control like my classic 2007 silverado, then you have seperate actuators for each side.

here.. i just did a quick search... try this:

linky1

and here is another article on this....

linky2

both articles mention a code that was thrown... put on a scan tool and see if there is one by chance...

just another thing to try...

Any typical code reader will do you no good and some aftermarket (snap on) scanners also won't read HvAc codes of data.

If it would not change mode then I could see an actuator being a possable problem. But since there is no control(temp) I don't see that because I have yet to have a faulty actuator lock up the logic withing the module/head.

Zoediak · Dec 28, 2011

crash said:
Any typical code reader will do you no good and some aftermarket (snap on) scanners also won't read HvAc codes of data.

If it would not change mode then I could see an actuator being a possable problem. But since there is no control(temp) I don't see that because I have yet to have a faulty actuator lock up the logic withing the module/head.

well, sadly, i have had this problem... after the job was done and battery hooked back up, all it would do is blow hot air out the AC vents... could not change them and could not change the temp.

after following a reset procedure, was able to get them back to the proper position and working again...

it doesn't cost anything but some time to give it a try....

crash2 · Dec 28, 2011

Zoediak said:
well, sadly, i have had this problem... after the job was done and battery hooked back up, all it would do is blow hot air out the AC vents... could not change them and could not change the temp.

after following a reset procedure, was able to get them back to the proper position and working again...

it doesn't cost anything but some time to give it a try....

Yes its a good try but I have seen way more not fix it than I have seen fix it

CHOP SHOP · Dec 28, 2011

I love my dodge.

crash2 · Dec 28, 2011

CHOP SHOP said:
I love my dodge.

If we loose our vacuum pump we are **** out of luck to. And I think the newer dodges have gone electronic head units also. Plus the didge heads will flake the paint off the head unit faster than the chevs do.

skinny_pedal · Dec 29, 2011

CHOP SHOP said:
I love my dodge.

Better plan on keeping it forever because technology is only getting worse for the diy guy. I know manufacturers ultimate goal is so the average guy can't work on his rig.