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.
May 18, 2006 at 3:15 AM
1994 Chevrolet 3500 Heater Click
RANDY BAKER
- MEMBER
- 2 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.
May 18, 2006 at 10:38 AM
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.
May 22, 2006 at 12:46 AM
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
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
May 22, 2006 at 1:07 AM
Suggested Repair
Isolate the clicking vent door by turning the A/C off and trying different control positions. Unplug and remove the small flat black door motor near the noise and move its arm by hand to confirm the source. If the flap is loose, block it from moving if possible; otherwise the dash and full heater/A/C assembly must be removed, which requires discharging the A/C and removing the steering column.
Conversation Summary
A 1994 Chevrolet 3500 dually diesel clicks under the dash by the heater box at startup, shutdown, and with A/C on max. The owner felt a flapper hammering. The expert suspects a motor-driven vent door and advises isolating the motor, then either blocking the loose flap or removing the dash and heater/A/C assembly.