Bottom and middle blowers work fine, defrost only has a bit of air coming out onto the windshield, and I think it's getting worse. When it clicks over to defrost I hear whistling shortly after, and the whistling increases the faster I drive.

I'm assuming the flap or something in the dash is stuck, does anyone have any ideas what it could potentially be? Could I get at it without tearing the whole dash apart? I'd rather not take it to a shop and pay 3 hours in labor just to find out whats wrong, plus pay to fix it, if I can do it myself it would be much better.

I read another, ancient at that, post in a 92 where a guy just said some gears needed grease, but he didn't get into detail on where...

People seem to hate posting in old threads.

Help would be appreciated :)

My '94 does the same thing every winter, you need to unbolt the radio control box, and look up at the heater box there is a series of levers and a motor watch the levers as you switch from floor to defrost one of the levers will be stuck just reach up there give it a little nudge and that should free it up. The rubber flap that seals the duct gets stuck after not being used for a while. Hope this helps.

My '94 does the same thing every winter, you need to unbolt the radio control box, and look up at the heater box there is a series of levers and a motor watch the levers as you switch from floor to defrost one of the levers will be stuck just reach up there give it a little nudge and that should free it up. The rubber flap that seals the duct gets stuck after not being used for a while. Hope this helps.
Is it difficult to get to? Can you take a photo if it is? I'd like to try it myself rather than a shop.

I got a PM from somebody with the same problem as me, he identified the actuator and told me where it is, I found it, but I'm not sure how to identify if it really is the problem.

Thanks for the reply!

Sorry no picks. You have to move the radio control box to get easy access to it, it is only held on with to bolts, you just push it toward the gas pedal. The lever that I am talking about is just above the accuator, if you watch as you switch from floor to defrost you will be able to see if the accuator is working and beable to see what parts are not moving.

Sorry no picks. You have to move the radio control box to get easy access to it, it is only held on with to bolts, you just push it toward the gas pedal. The lever that I am talking about is just above the accuator, if you watch as you switch from floor to defrost you will be able to see if the accuator is working and beable to see what parts are not moving.

I'll have a look when the weather is warmer than -17ºC :)

The actuator looks like http://198.208.187.182/internet/ViewPartImage.jsp?acdelcoPartNumber=15-71937 and in my case, it was too weak to move the mode door.

I remove it but left the wires hooked up and then changed from vent to defrost and it barely moved.

If you need to replace it, you can find it at any AC Delco parts store. It will be more expensive at a dealer.

//2000CAYukon

Had a look, turns out the linkage had popped out...I still don't think it's opening all the way though. We'll have to wait and see.