No heat coming out of windshield defrost vent .no blowin air

SOURCE: Air only blows outthe defroster vents on top of the dash

unhook battery, rehook battery, turn key on, ..............wait 2 minutes, then start truck and ck a/c. sometimes it works, if not, it will need to be checked by a shop .

Posted on Sep 24, 2009

Marvin

• 85239 Answers

SOURCE: HVAC duct

This is caused by a loose of vacuum to the mode control switch, the vacuum line runs through the firewall on the passenger side near the kick pad trim.

Posted on Nov 05, 2008

SOURCE: Heat or air only comes out from window defrost.

try changing your whole heater switch unit that should work

Posted on Dec 09, 2008

SOURCE: Heat wont blow through heater or defroster vents

common problem, check under dash by the gas pedal if control arms are muving went selecting from ac to heat cuz this it is the control for the vents to go from ac to heat and to defrost.

Posted on Feb 23, 2009

SOURCE: All Air Conditioning blows our the defrost vents

Some thing you could look at would be this. The control is usually fed by a vacuum line or small hose thats is connected to your intake manifold.
With a cold engine,look for a skinny vacuum hose that runs from the intake toward the fire wall . It should be going inside the cab and connecting to the A/C vent control.Some times the hose becomes disconnected or splits or cracks due to heat under the hood.
Thats usually the trouble.
I hope this helps you.

Posted on Oct 06, 2009