Heat comes out of dash vents. When I switch to floor vents, heat still just comes pout of Dash vents and not floor vents.

SOURCE: There is no air flow

You need part GM Part number 89018675 or ACDelco 15-73596. The Mode Selector Actuator. What happens is the part is a CHEAP part POORLY designed and when it goes to turn the flaps inside the HVAC unit its the plastic gear slips instead of turning the flap!!!

Just to forward you you might want a deal to install this art for you unless your good at fixing your own vehicle, because you need SMALL sockets and a lot of patience to get this part in!!!

The part is ALMOST directly above the steering shaft for your steering wheel, so theres a lot you got to remove before you will even see them!!!

I only recommend you to have a dealer put this part in for you, unless you have your own service manual!!

Because there is 5 of these darn things and if you pick the wrong one you will have to do it all over again!!!

3 on the Drivers side and 2 on the Passengers side!!

But replacing this part SHOULD solve all your problems!! AS it did for me and i was having the same issues as you have described!!

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.

SOURCE: Heat wont blow through heater or defroster vents

The door in the heater box is most likely stuck. It is located under the dash on the passenger side

SOURCE: Front windshield defroster not engaging on 1999 - 1500 Silverado

i just went thru this problem with my 95 1500. on mine it was the controls just like you discribe on yours one for fan one for temp and one for settings.first i thought it was the heater blend door acturator. its located on left side of heater next to the gas peddel. pulled the wire plug out and test for power theres 3 wires to this plug one white one brown and one black. the brown wire was hot with key on the black is ground and the white is the one that sends a siginal to this electric motor witch redirects air flow from floor to dash vents to defrost. i had to order the controls thru autozone 135.00 with shipping. you might get lucky and find one at a bone yard the ones in my area dident have any. i almost bet you will find thats your problem too. good luck OLD SCHOOL.

wyet

• 510 Answers
• Posted on Jun 10, 2011

SOURCE: 2003 Chevy trailblazer, the 4 front dash air

{: ) Check first the fuse labeled HVAC1 10A at the rear fuseblock. If okay, the mode actuator could be faulty. You can try this: turn ignition switch and a/c off for a minute. Then turn ignition on, wait forty seconds. Afterwards, start the engine, and check your a/c again.