'99 A/C vents,air flow question.
 

Hi all,

I have a '99 GMC Sierra 1500 with the 5.3 liter V-8. For some reason, every few months the air conditioner compressor belt breaks. Well, this time, it broke around Christmas and I didnt bother to fix it, being as that it was winter.

Ive now replaced the belt, but the air flow for the A/C only blows from out of the defroster ports. Regardless of the switch (dial) position, it wont shift to the dash. I have it set for recirculation, instead of fresh air. However, when I turn the dial from the legs/face to the defrost, it switches from recirc to fresh air. So, I think the switch works.

I cant see that any of the fuses are bad.

Does anyone have any suggestions? Thanks in advance.

Check your blend doors motor/actuator. On GMs and Fords there are two that are connected to the large black plastic chamber underneath your dashboard. They control the movement of the air going either through the dashboard, the defroster or down onto your feet. Are they air/vaccuum actuated? electronic or levers on the dashboard? If they are air/vaccuum actuated you will hear a soft ppppsssshhhh when you change the AC/HEAT controls. If electronic its silent but the dashboard controls are probably push button. If a manual lever controlled then its a linkage problem.