Blower motor
 

Can someone please tell me what the hell is a flapping sound coming from the blower motor area on my truck. It makes the sound when I start the truck and when I turn it off. And after I turn off the heater. The sound doesn't last long maybe about 15 seconds or so. My heat works fine and the ac works also. Its a 1994 gmc silverado truck 350 5.7 2wd.

Re: Blower motor
 

The recirc door opens when you turn off the truck so the air pressure from shutting the door doesn't prevent the door from shutting. It will close when you start the truck.

Re: Blower motor
 

Okay, but what is the flapping sound im hearing ? That is my question.

Re: Blower motor
 

Or i should ask why is it making a noise.

Re: Blower motor
 

Only one way to find out, take it apart and have a look. There are no cabin filters in these trucks, so something could be in there that's not supposed to be.

Re: Blower motor
 

bad actuator trace the faulty unit.

Re: Blower motor
 

Where is that pesky thing located?

Re: Blower motor
 

youll need to climb under dashboard turn ignition on

to find the noise flapper moving up and down.

i think our chevys theres 3 of them.

Re: Blower motor
 

You can reach under the dash, behind the blower motor and move the flap with your fingers. Try that first, and see if it makes noise. then try to find if something is in there that should not be.

You can replace the recirc door actuator with a little bit of patience and a 1/4 air ratchet if needed. It's tight in there so a regular ratchet won't work.

Re: Blower motor
 

Re: Blower motor
 

That thread was just what I was looking for. Chevy Tech does it again. Awesome info.

Re: Blower motor
 

I replaced nearly everything in my truck ( '88 GMC 2500 w/ 378,000)

I replaced my blower motor & barrel fan. The darn fan seems to make a slight knocking sound sometimes. I looked / reinstalled 3 times ( even got another fan exchange from auto parts).... Beats me.... it seems to fit .....

Re: Blower motor
 

Check out Scottys Detailing on YouTube he posted a video last night about the hvac on our body style Chevy trucks . It's got some good info.

Re: Blower motor
 

ok i was wrong only one that controls all 3 vents

i found a video might work for u, just lube the spring and mechanism
under dash might work for u.
https://www.youtube.com/watch?v=YDpLZZaih9c

Re: Blower motor
 

Thanks diveplane. Thats perfect. Good work.