Heater / AC I have a Grand Prix and when the.

Tiny
TRAVISBEATTIE
  • MEMBER
  • 1998 PONTIAC GRAND PRIX
  • 197,000 MILES
Heater / ac I have a Grand Prix and when the heater or a/c is on it blows through vents floor and windshield no matter what setting I have it on now if u hit a hard bump it will fade to the one that it is set on any solution for this
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Wednesday, February 22nd, 2012 AT 3:56 AM

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Tiny
TRAVISBEATTIE
  • MEMBER
The heater or a/c blows through every vent no matter the setting but when u hit a hard bump it blows through the one its set on
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Wednesday, February 22nd, 2012 AT 3:58 AM
Tiny
BILLYMAC
  • EXPERT
Hi you have a blend air door sticking possibly just stuck or vacum hose to it leaking. Look under dash watch levers moving while you change vents with car running you will find a problem with a blend door.

If no prob there check vacum at vacum resavoir under the hood
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Wednesday, February 22nd, 2012 AT 4:02 AM
Tiny
TRAVISBEATTIE
  • MEMBER
K thank you if it is stickin what could u put on it so it dont stick and qouls I have to take anything apart to do it
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Wednesday, February 22nd, 2012 AT 6:38 AM
Tiny
BILLYMAC
  • EXPERT
No you don't have to take everything apart. If it is sticking something is prob stuck in it if not just spray a little wd40 on the hibges
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Wednesday, February 22nd, 2012 AT 1:27 PM
Tiny
TRAVISBEATTIE
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K thank you
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Thursday, February 23rd, 2012 AT 1:14 PM
Tiny
WRENCHTECH
  • EXPERT
The mode door is electric and for temp control only.

The mode selection is done through a series of air doors that are operated by vacuum. When there is either a partial or total loss of vacuum, the system will default to either defrost or on some vehicles, heat. Acceleration can also have an effect on the doors for the same reason.

Look under the hood for a small black plastic hose coming through the firewall. Follow it to the vacuum source looking for any breaks, cracks or leaks. Also follow any other lines that branch off because they may go to a vacuum reservoir (storage tank) and a leak there will cause the same problem. Using a vacuum gauge to determine if you have full vacuum at any given point is the best way to find it. You can cut into the line anywhere and splice it back together with a piece of vacuum hose. Find the broken line, you found your problem.
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Thursday, February 23rd, 2012 AT 1:32 PM

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