HVAC controls not telling blower to turn on, intermittent

[hillstrubl]

if any of you have a tech2 you could try commanding the fan on when this happens if it does not respond or does respond but the controller won't change it alone. then I would certainly suspect the controller.
also check for any hvac system codes. blend door feedback codes are very common but most likely not the issue in this case.
you could also maybe check and see what the comanded state of the fan is versus actual. (if there is such a option in the tech2)
mine is in the shop for a couple more days so I can't offer much more help at the moment.

***also I assume all of you have the digital control? or is this happening with the manual controls also?

I don't have a tech2 unfortunately

A digital control pannel will need programed to work.

Dorman's is claiming it doesn't? Any truth to that? part is 599-142


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Is there any chance the HVAC control panel is ok and its the blowers that aren't waking up?

 

[Doubeleive]

6-months later....... lol probably getting cold now eh

 

[hillstrubl]

6-months later....... lol probably getting cold now eh

Its intermittent, maybe 1 out of ever 10 times I drive it. When it does happen a bump within the first 10-15 min of driving usually wakes it up.

Only 1 time so far have I been able to get it to wake up.

 

[Doubeleive]

Its intermittent, maybe 1 out of ever 10 times I drive it. When it does happen a bump within the first 10-15 min of driving usually wakes it up.

Only 1 time so far have I been able to get it to wake up.

Hmma.ybe try cleaning the harness connector

 

[hillstrubl]

I'm going to do that next, I just tried the reset (pull fuses with ignition off for 10 seconds, reinstall, start engine and don't touch anything for 40 seconds). The blowers kicked on for a second, then off/very low, then sounds like they were trying to turn on and failing for ~20 of those 40 seconds, then kicked on high. So weird...

 

[mikez71]

Dorman's is claiming it doesn't? Any truth to that? part is 599-142

I swapped to a used unit, no programming required. Perhaps new OEM ones come un-programmed? I think GM just wants to charge for programming anytime anything is replaced..

 

[mikez71]

Original blower motor?

 

[hillstrubl]

Original blower motor?

Yes, please tell me the whole Dash doesn't have to come off to replace it... Should I do the panel first?

When the blower kicks on its strong, no squeaks, issues, I would think a failing blower motor wouldn't go full speed?

 

[mikez71]

Control panel easy, just need to pry the radio surround off. Then remove multifunction switches, then hvac module.

Blower motor not bad either, just need remove underdash panel first, middle screw need to reach from the side..