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2003 Chevy Blazer heater control module vacuum

Tiny
REDSOXROCK67
  • MEMBER
  • 2003 CHEVROLET BLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 84,000 MILES
I noticed the other day a "hissing" noise coming from my heater when I used the controls. When I turn the heater control to the different settings the air flow stays in the same location and does not come out of the selected setting. For example, the air flow now comes out of the front dash vents in full force and if I change the setting to the floor vent it still comes out of the front dash vents. If I close those front dash vents it is then rerouted to the floor vent but not near as strong of force as previously. If I set the setting to the windshield defrost the air flow is not as strong and if I open the front dash vents it comes out of there in full force even though the setting is still on windshield defrost. Whereas previously the only time the air flow came out of the front dash vents is when I specifically selected that setting.

Can you help?
thanks,
Craig
Ottawa
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Friday, April 23rd, 2010 AT 7:42 AM

3 Replies

Tiny
INTERNETMECHANIC
  • MECHANIC
  • 700 POSTS
Have hvac codes checked. Check the vacuum lines under the dash. Check for tranny fluid in hvac vacuum lines, I saw a service bulletin about that. I can't be positive of your problem, at the moment?


https://www.2carpros.com/forum/automotive_pictures/512072_hvac_vacuum_1.jpg

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Friday, April 23rd, 2010 AT 11:32 AM
Tiny
REDSOXROCK67
  • MEMBER
  • 3 POSTS
Thank you for the prompt response! I will follow your suggestions and let you know the result.

Thanks again!
Craig
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Friday, April 23rd, 2010 AT 12:17 PM
Tiny
REDSOXROCK67
  • MEMBER
  • 3 POSTS
The issue has been resolved and was due to a minor tranny fluid leakage. Thank you again for your assistance!
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Thursday, April 29th, 2010 AT 8:22 AM

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