1992 GMC Sierra .no air flow from AC ducts

[z50kidd]

I have a 1992 Sierra Ext Cab,it has been a great truck.
I have had it for about 10 years 168,000 miles on it,it still runs great.
I have a problem with air flow in the ac/heater.It moves from vent to defrost to floor with no problems.But not much airflow comes out.When I first turn it on ,you can hear what sounds like a flapper in duct go thump.The re-circulate button does not seem to do anything when I push it,but the light comes on, REC.Help !!! it is smoking hot in summer down here in Florida..............Z50kidd

[2000CAYukon]

On my 90 K1500 (original owner 115K), the mode door actuator would not move all the way leaving the door in the wrong place. Not much air came out especially the defrost (during winter) stopped working. Basically, I took it apart and put some white grease on the gears. Threw it back in and it has been working fine ever since.

Or you could just replace it. The mode door actuator is under the dash on the drivers side just above the tranny hump. Take it off but leave the electical connected. They you can move the door by hand to see if air flows.

With the electrical still hooked up, you should see the piece turn as you change from vent to defrost. In my case, I could see that it was not turning very well. Of course it was 15 years old too!

//2000CAYukon

[z50kidd]

What all is involved in taking this apart ???

Originally Posted by 2000CAYukon

On my 90 K1500 (original owner 115K), the mode door actuator would not move all the way leaving the door in the wrong place. Not much air came out especially the defrost (during winter) stopped working. Basically, I took it apart and put some white grease on the gears. Threw it back in and it has been working fine ever since.

Or you could just replace it. The mode door actuator is under the dash on the drivers side just above the tranny hump. Take it off but leave the electical connected. They you can move the door by hand to see if air flows.

With the electrical still hooked up, you should see the piece turn as you change from vent to defrost. In my case, I could see that it was not turning very well. Of course it was 15 years old too!

//2000CAYukon

[2000CAYukon]

As I recall, it was held together with some small screws. It was pretty straight forward. I fixed it during the winter and it is still working fine.

Just be carefull pulling the case apart and you should be fine. Otherwise, just replace it.

//2000CAYukon