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**Wrenchbender Ret** · 09-13-2015, 05:23 PM

There is a box under the dash that has a diverter flap in it. These are nortorious for going bad. The valve comes loose & won't let the air go through the core.

09-13-2015, 05:23 PM	#6
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,194	Re: 71 GMC Factory Air Problem There is a box under the dash that has a diverter flap in it. These are nortorious for going bad. The valve comes loose & won't let the air go through the core.