Defrost / fans not blowing air in front seats.
Could be caused by a fault w/the HVAC air directing doors.
Have you checked if the blower fuse has blown?
Tester
The seat ventilators have their own fans, these are separate from the A/C and heating unit.
With the little info you gave, I would first do what Tester suggested and check for a bad fuse.
If you are referring to the cooling of the seats, then…
the cabin air is drawn through the ventilation cooling
module air filter, then directed through passages in the foam of the seat
cushion and seat back. The system is not hooked up to the HVAC system it draws
cabin air. The system blows thru the cushions on the seat back and bottom
Here is the possible reason and the solution …under your seats (front driver side and passenger side) there is a blower motor under the butt cushion. This blower motor is to be connected to a flat duct made of a rubbery, mesh filled membrane. This “duct” connects the blower’s airflow up and into the seat butt cushion where the air is supposed to be released. The problem is that over time, this rubbery membrane, which is supposed to be the airflow duct, deteriorates (I believe it is primarily made a very thin latex rubber which degrades over time like an old Halloween mask or something). The end result of which basically creates airflow with nowhere to go because there is no longer a sealed duct to force it into the seat cushion. As for the airflow to the back of the seat? Well, if you remove the panel from the back of your seat, this very same “membrane” duct is there too…ducting the airflow from the seat’s upper blower into the back of the seat cushion.
I have found a site that shows a possible DIY fix. it is on a 2010 Acadia but might give you an idea on what to do.
My Ventilated / Cooled Seat Duct/Membrane Repair Process | GMC Acadia Forum
If you are talking about your heated seats not working, then this is some info on that…
Heated Seats Not Working? GM Car Seat Repair Tips - 1A Auto
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Thanks for the response! How can I check and/or repair? Thanks again!
It isn’t a fuse because it works sometimes and other times does not. Specifically referring to defrost, ac, heat only. Not referring to the seats, themselves. Thanks, everyone for your input!
The next time the blower stops working, with blower speed set to high, reach under the passenger side of the dash and with the handle of a screwdriver rap on the blower motor.
If the blower starts working again, the blower motor needs to be replaced.
Tester
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When it seems to be working, do you hear the blower fan noise? Then when it doesn’t work, do you not hear that noise? If you aren’t sure about the fan noise, try varying the fan speed, you may be able to hear the pitch change.