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HEATER CONTROL

Tiny
RANDY BAKER
  • MEMBER
  • GMC C3500
Everytime I start my truck or shut it off I get a clicking sound under my dash over by the heater control. My truck is a 3500 Dually diesel.
Thursday, May 18th, 2006 AT 10:15 AM

3 Replies

Tiny
LOSONE
  • MECHANIC
  • 1,616 POSTS
Turn the A/C switch off and see if it clicks. Then try various positions so we can isolate the source of the click.
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Thursday, May 18th, 2006 AT 5:38 PM
Tiny
RANDY BAKER
  • MEMBER
  • 2 POSTS
I Have a 1994 Chevy 3500 Dually Pickup With a 6.5 Turbo Diesel Engine. My problem is when ever I start or turn off my truck I get this clicking noise under the dash by the heater box. I felt under the box a found a flapper of some sort hammering but I couldnt see it. It also does it when I turn the AC on max. Please help me it driveing me crazy! Thank you.
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Monday, May 22nd, 2006 AT 7:46 AM
Tiny
LOSONE
  • MECHANIC
  • 1,616 POSTS
I am not there but I suspect that the "flap" is the vent door that diverts air from outside to inside.

There flaps are driven by a motor attached to each area, defrost, heat, air etc.

In the area of the flap noise unplug and remove the small, flat black motor and move the arm by hand. If you can replicate the noise then you have isolated the problem.

Regardless you will have to remove the dash and then the entire A/C-heater assembly uless you can find some way to block the flap from turning.

It is a 12-15 hour job because the A/C has to be discharged, steering column out, dash out and then you can get to the assembly.

Hopefully you can find which flap is loose and block the movement. One of GM's better ideas.

Good luck
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Monday, May 22nd, 2006 AT 8:07 AM

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