1991 GMC Sonoma Q&A
1991 GMC Sonoma Question: The vents on the truck are stuck on defrost and floor vents. Need help.
What needs to be replaced to make the vents get off the defrost and floor vents. The A/C works fine and also the blower motor. My only problem is I can not change the vent setting off of the defrost and floor vent setting. What can be the problem. Is it some vacuum hoses that are not attached are the control switch for the vent setting. Please help me out with this. - jrich4344
look under the hood from the vaccum canister to the firewall by the pass side you may have a broken vac hose that controls the a/c and heater vents. if you can't find it and you have access to a smoke mach that will find it. - globalhelper
Agree, most likely a cracked or loose vacuum line in the engine compartment that needs fixed or reattached. - csubak30