First bit of cold weather and I’m getting thirty seconds of loud clicking (or clacking) coming from the immediate vicinity of the blower motor on start up and shut down. Doesn’t matter whether my climate control is on or off, it still makes the noise. I’m assuming it’s stripped out teeth on one of the blend door actuator gears and I’ll probably just end up replacing it. My problem: Where exactly is the offending actuator? I’ve removed the glove box and noted one located on the left side. I unplugged this but am still getting the ratcheting sound so it obviously isn’t the culprit. I had this happen a few years back (same time of year) and out of ignorance and frustration solved it with a well aimed kick but the way it’s acting this time I don’t think I’ve got a big enough boot.
You need to look up under the dash between the blower housing and the distribution plenum to locate the actuator. Here’s what it looks like.
This may be irrelevant, but…on my 98 Tahoe, I have some problems with switching the blend, to have air coming out of the upper AC vents or not. It seems that something is “sticking”. I find that it helps to turn the heat up, then put it into the position you want, and wait. Sometimes it takes a few minutes before the doors move into the correct position. Having hot air blowing thru there definitely helps.
The actuator has nothing to do with the vent system. It’s function is to allow air to escape the cabin whenever the door is slammed shut.
When the door is opened, the actuator opens the vent door so when the door is slammed shut pressure doesn’t build inside the cabin preventing the door from closing. Once the door is closed, the actuator then closes the vent door. The same thing happens when you leave the vehicle. When you open the door the actuator opens the vent door preventing pressure from building inside the cabin when the door is slammed shut. Then the actuator closes the vent door.
If you’ve ever seen the actuator fail where it doesn’t open the vent door, you could try to slam the door shut all day long and it would never close completely. To get it to close, the door would have to be closed slowly.
I had this door closing problem w/a VW Rabbit, hard to close the door. I learned to roll down the window 1/2 inch first to allow the pressures to equalize. It sounds like the actuator is supposed to accomplish that task automatically, but is failing for some reason.