Heater blows through vents but not lower

Tiny
MISSINGVOREE
  • MEMBER
  • 2001 CHEVROLET TAHOE
  • V8
  • RWD
  • AUTOMATIC
  • 197,000 MILES
My SUV has a 5.3L engine. The heater blows through all vents hot, switch to the lower setting, nothing.
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Friday, December 30th, 2016 AT 7:11 PM

7 Replies

Tiny
STEVE W.
  • EXPERT
If you mean it blows through the dash vents or defrost vents but does not change to the floor vents then you have either a mode door actuator or mode door failure.
Not a hard repair. Basically you put the passenger seat back, go into the passenger footwell. Remove the heat duct extension from the end of the HVAC case with a few screws. Right above it will be the mode control actuator. Remove the screws securing it, rotate it out so you can see the drive, now switch from defrost to vent to floor. If the actuator motor does not move, it is bad. If it does the door inside the case has failed. That is a bit harder to change.
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Saturday, December 31st, 2016 AT 12:58 AM
Tiny
MISSINGVOREE
  • MEMBER
Thank you, Steve. Would you by chance know the part number for the actuator motor that may need to be replaced. I would like to have one on hand when I remove and replace. I am glad I found your site. Thanks again.
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Saturday, December 31st, 2016 AT 4:18 AM
Tiny
HMAC300
  • EXPERT
Try pulling fuse for that HVAC unit for sixty seconds sometimes they reset without having to replace it.
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Saturday, December 31st, 2016 AT 6:48 AM
Tiny
STEVE W.
  • EXPERT
The part number depends on which actual system you have. They all use the same HVAC plenum and parts, but the actuators depend on if you have manual, automatic or dual zone heat controls. There are three different parts to cover those options.
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Saturday, December 31st, 2016 AT 9:28 AM
Tiny
MISSINGVOREE
  • MEMBER
Fuse pull did not work. Pulled the lower actuator, this is the one that blends the hot and cold, it worked fine. Air Door Actuator that controls upper and lower air is Oreilly part number 604-114. Any idea of which one is the upper and lower control actuator location. Thanks
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Saturday, December 31st, 2016 AT 1:19 PM
Tiny
MISSINGVOREE
  • MEMBER
604-113 is the correct part number
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Saturday, December 31st, 2016 AT 1:20 PM
Tiny
STEVE W.
  • EXPERT
The mode door (defrost/vents/floor) is the one on the side of the HVAC plenum.
GM part #52473356

The blend door is the one at the bottom of the plenum (hot/cold) GM part #52474810
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Saturday, December 31st, 2016 AT 2:08 PM

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