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Old 05-05-2009, 07:48 PM   #3
ChevyTech
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Join Date: May 2004
Location: Minnesota
Posts: 4,620
Re: Does a 96 GMC Sierra have in Cabin Air Filters?

The think the first year there were cabin air filters in GM trucks was 1999, and NOT all 1999 trucks had filters.

By 2004 GM stopped putting cabin air filters in the trucks.

My first guess would be the “recirc” door aka fresh air door, is not operating correctly. Each time you shut off the engine the fresh air door should open if it is not already open. When you change settings from recirc to max ac the door should open, and if you listen carefully you should be able to hear it.

Another possibility is that there is debris like leaves and seeds blocking air flow. I have seen blower motor fans fully of leaves and AC evaporators plugged up with cottonwood seeds.

It is also possible that the mode door in the heater box is damaged or catching.
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