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JFN1, ASE Certified Technician
Category: GMC
Satisfied Customers: 4607
Experience:  GM Master Technician
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1999 gmc safari ac was running on max the heater temp

Customer Question

1999 gmc safari ac was running on max the heater temp control was selected to full hot by mistake . now fan runs but no flow to the vents ac or heat any suggestions of what might be wrong
Submitted: 2 years ago.
Category: GMC
Expert:  JFN1 replied 2 years ago.

On these vans, the most common cause for the airflow problem you're having is the vacuum supply from the engine. The vacuum hose runs from the right side under the hood, across the intake manifold and connects to a fitting on the manifold. This hard plastic line usually gets brittle and breaks in two right at the manifold. You'll have to move the air filter housing out of the way, but you'll likely find the solution to your problem on top of the engine.

Customer: replied 2 years ago.
thanks but the problem was the flaps in the heater box were stuck restricting the air flow. will I now get a refund .