Help with the flapper flapping ???

[Dieseldad97]

A friend of mine has a 1994 Burb and whenever he starts the truck and turns on the air cond. the flapper will flap for a minute or two. He turns the key off and it does the same thing. Make sense? The noise is coming from the plastic shroud beside the fan.
I told him I'd throw the question out there.

Any ideas?

 

[DieselCash]

Mine does the same thing when I actually use the A/C system.

I have not had the time or effort to look into this yet. I also have not been able to guarantee the repeat of it, which would make diagnosing the problem easier.

I am curious if this is a 93 - 94 problem or do our newer generation trucks(95-99) have the same issue?

Maybe once I get my front end issues fixed I can concentrate my time and money on the flap issue! :mad2:

 

[GM Guy]

got it on the 91. there is an article out there somewhere written by someotherguy of fullsizechevy.com fame. I beleive it is the blend door actuator. I beleive it is only on a/c equipped trucks. basically the control module cannot "see" the position of the door, so it switches it back and forth trying to get a reading. basically, the motor is good, the sensor part of it isnt. It has to be replaced, and can be done with no dropping of dash, but it is a bitch. I still have yet to do it on the 91 gasser, it has been that way since I bought it in 06. got the motor and everything. what a lazy ass I am.