noise from dash on 04 Sierra

[vanisland2004]

I am getting a strange grinding/pumping noise (impossible to describe) coming from behind the left side of my glove box and towards the center of the dash.It only happens when the key is on and reduces/ goew away while blower motor is running. My 'service air bag' light has also just come on, anyone experience anything like this before or have an idea?

 

[Molson02536]

I am getting a strange grinding/pumping noise (impossible to describe) coming from behind the left side of my glove box and towards the center of the dash.It only happens when the key is on and reduces/ goew away while blower motor is running. My 'service air bag' light has also just come on, anyone experience anything like this before or have an idea?

Sounds like your heater vent actuator has gone bad and will need to be replaced or cleaned. The greased used to lubricate the actuator will cause the actuator to get lost it it's setting and will keep pulling on the vent door thinking it's still open when it's already close.

The actuator is make of plastic and after a few years, the heat will cause the plastic parts in the actuator to brake and then when it totally fails. you have no vent or temperature control due to a broken actuator.

Here is a link that should help you with this issue. As for the air bag light, that is a different issue and your going to have to take it to the dealer and have them hook up the scanner to address the air bag issue you are having.

http://gmcowners.com/gmc-forum/showthread.php?t=15819