I have a 99 chevy Blazer. I want to check my Vent door actuator, but don't know exactly where it is. Can anyone show me some pics, a website or how I can get some pics? My Haynes book doesn't show you where it is? I know it's behind the dash.

 

you can get to it through the glove box, w/ the door open there's a u shaped wire in the upr Lt, push it up and the door will drop down, the act will be to the left, if you have manuel A/C controls they're vacuum oper and you have to check for vac @ ea diaf . as for pics you can try an older small GM dealer and ask if you can look at a service manual for that specific mod/yr if they still have them. newer bigger dlrs are computerized and won't give ya the time of day.

 

LOOK WHAT I FOUND!
REMOVAL PROCEDURE
The electric actuator (temperature) is located on the top right hand side of the heater/vent module.

1. Remove the instrument panel carrier.
2. Disconnect the electrical connector.

1. Remove the electric actuator retaining screws.
2. Remove the electric actuator from the heater/vent module.

INSTALLATION PROCEDURE

1. Install the electric actuator to the heater/vent module. Ensure that the actuator is seated on the locating tab.

NOTE: Refer to Fastener Notice in Service Precautions.

1. Install the electric actuator retaining screws. Tighten Tighten to 1.9 N.m (17 lb ft) .
2. Connect the electrical connector.
3. Install the instrument panel carrier.
4. Perform the following procedure in order to Initialize the electric actuator on vehicles equipped with automatic climate control (C68).

5.1.Turn the ignition switch to the OFF position.

 

Look what I found:
2nd Gen Temp Door Actuator Replacement
With proper pictures... LOL

 

I don't know what happen. After I posted the instructions it was correct. I got the info from alldata. Anyway if anyone is having this problem, check your ambient air sensor about $60 at the dealer. It's located above the drivers side door in the headliner. Well at least on my 1999 LT Blazer. I guess it talks to the climate control computer. I replaced it and like magic everything works now. The blend door actuator is not acting crazy anymore. There is a easier way to check the door without riping apart the dash too. Under the hood next to the blower there is a label that says "cut here". If you cut it open and unscrew the cover you can watch the flapper move according to your temp settings. I hope this helps anyone with this problem. It was a real headache for me and couldn't find any info on it. Not a very common problem.

 

That is one of the problems with posting alldata hosted pictures. They cycle their images to make it difficult for people to hot link to their images.

That 'cut here' under the hood is for access to the blower motor resistor pack. It won't get you anywhere near the blend door actuator.

The problem with diagnosing the automatic climate control is that it is another one of those separate systems in these trucks. Without testing out sensors, it is difficult to say what is causing the issue. The most common cause of a cycling blend door and the majority of blend door issues is the electronic actuator itself (well, actually the gear inside).

Glad you got your problem fixed and thank you for the follow up!

 

I am new to this site, so excuse me if there is a better one posted here, but this is thread I used to figure mine out.
http://www.automotiveforums.com/vbul...d.php?t=574779