No it does it while in PARK, Drive, stopped at speed. Seems really random.

Blower speed has no effect. Does it in all positions.

Truck.m4a - 0.62MB

Sound of noise in truck.

 

If it doesnt do it going down the road this would rule out air flapping something. If the engine speed doesnt affect it this would rule out motor or components. Also sitting still would rule out drive line. You can only hear it in the cab so this puts it back to heater. Im going out on a limb and GUESS you have a broken plastic arm on a mode door motor. It keeps trying to operate it and cant. This would require some disassembly to verify.

 

This could be it. In my case my wife has been complaining about no heat on the passanger side when i have it selected floor vents.

 

Thanks guys Hopefully that narrowed it down enough for me to cure

 

Would pulling a certain fuse or fuse's help determine exactly what this is? Or narrow it down?

Such as pulling the AC blower motor fuse or something? If so, which fuse should I start with?

 

Bump....

 

The silence is probably because there really isn't anything. The HVAC control module is supplied by the HVAC fuse except for the blower control switch, by the HTR A/C fuse. There is a Blower fuse but that only comes into play with the blower at the highest setting. Pulling the HvAC fuse shuts down the HVAC control module and thus it's going to be no help.

If an air/blend door actuator is out of sync, you'll have to get it serviced. It may just need to be relearned with a scan tool.

 

BayAreaChevyGuy, have you gotten this issue resolved yet?

Jeff Morris, Chevrolet Customer Service

 

I have the same issue with my 2003 2500HD. It doesnt always happen but when it does its usually after about 10-15 minutes of the air being on. Also my air cuts in and out and I have to have my girlfriend give a little kick on the passenger side to get it to come back on... Any ideas on that? Im thinking loose connection and I just havent had the time to check, just want a second opinion.