Having problems with your 1999 Chevrolet Blazer ?
Switching from heat to defrost,still getting air coming out of vents
I have the same proble3m with my 01! with your car at idle do you hear a hissing noise coming from behind your vent controls? if you do you have a bad vacuum plungger on your heater nox under your dash! there are 3 of them to check one you can see behind glovebox and the other two are under bottom part of dash. you should be able to see them if you take off lower panel. the pluggers hold and push the doors inside of the hater box i bet one of those are bad! when you get them off the way to check them would be put your finger over the hole(off the truck in your hand) and they should stay still if they move still is bad a should be replaced
Vacuum hose may have came off
Repair Help & Product Troubleshooting for 1999 Chevrolet Blazer
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