Air conditioner and heater is only blowing out the defrost vents

Tiny
WINK1212
  • MEMBER
  • 1999 CHEVROLET TAHOE
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 155,000 MILES
I only have air/heat coming out the defrost (some slightly through the floor) and I have already replaced the blend door actuator under the floor pedals. The problems still exists, so what could still be the problem?
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Thursday, December 8th, 2016 AT 11:55 AM

6 Replies

Tiny
HMAC300
  • EXPERT
You need to check mode door actuator. Try pulling fuse first for sixty seconds with key on it may reset and be okay otherwise see one in picture. Blend door actuator is for temperature like heat to air conditioner.
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Thursday, December 8th, 2016 AT 12:01 PM
Tiny
WINK1212
  • MEMBER
That might be what I replaced (mode door), it was under the dash above the gas pedal. I replaced it and I see if moving when I change the controls from floor to defrost, but the blower still comes mainly through the defrost. The mode door controls where the air goes right?
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Thursday, December 8th, 2016 AT 12:11 PM
Tiny
KEN
  • ADMIN
It sounds like the blend door itself has broken loose from inside the heater plenum. But to be sure remove the actuator and work the pivot by hand with the heater on to see if the door makes any changes.

Please let us know happens so it will help others.

Best, Ken
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Monday, December 12th, 2016 AT 12:55 PM
Tiny
WINK1212
  • MEMBER
Ken, yeah I had did that a while back also, I pulled off the actuator and manually moved the arm up and down, but it didn't change any direction of the air/heat movement. So does that mean I need to pull the dash apart to fix? Thanks
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Thursday, December 22nd, 2016 AT 8:22 AM
Tiny
HMAC300
  • EXPERT
No you probably took the wrong one apart the pic shows correct one it may be a broken door or shaft
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Thursday, December 22nd, 2016 AT 11:44 AM
Tiny
KEN
  • ADMIN
If you moved the blend door pivot by hand while the unit was on and no air direction changed then yes the blend door is broken and the heater plenum needs to come out to be taken apart to see what happened.

Please let us know happens so it will help others.

Best, Ken
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Tuesday, December 27th, 2016 AT 8:27 AM

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