2002 GMC Sierra V8 Four Wheel Drive Automatic 97000 miles
when I switch the vent control to blow out of the dashboard vents and turn the blower speed to 3 or above, it creates a loud " blowing" noise behind the glove compartment area and ther is very little airflow from the vents
This is just a question I have to ask, but are the vent doors closed?
October, 26, 2010 AT 7:00 PM
Dang! I never thought to check that! Just kidding. Yes, all vent doors are open. I don't know how the internal venting system operates, but it seems to me that the plumbing to the dash vents is partially closed or something. The other vents (defrost & floor) seem to have plenty of air flow - just not the dash vents.
October, 27, 2010 AT 12:00 AM
Is this a manual system, or automatic control. In either case, is there air blowing elsewhere when full vent mode is selected(i.E. Floor or defog). Try this procedure and see if anything changes. The B+ fuse referenced is the radio fuse in the underhood fuse panel, it may reset your radio presets and clock.
The HVAC control module will relearn the actuator limits whenever power is disconnected and re-connected to the module.
Use the following steps to perform the calibration update: Turn OFF the ignition.
Remove the battery positive voltage circuit fuse of the HVAC Control Module.
Important: The scan tool must be disconnected from the vehicle to properly perform the calibration procedure. If a scan tool is connected before this procedure is completed, then new calibration values will not be stored.
Important: Failure to wait 60 seconds will not allow the HVAC control module sufficient time to clear the old calibration values.
Wait 60 seconds.
Install the fuse.
Turn ON the ignition.
Wait 60 seconds before installing a scan tool.
Also, if it is an automatic system, it would be interesting to know if there are diagnostic trouble codes in the system, that may point to a system fault. You would need a scan tool that would access the HVAC system.