Hey guys, recently swapped a 12k mile engine in the girlfriends 99 blazer, 4 dr, 2wd. It has the Automatic ac controls which I don't like . I kept the old compressor hooked up when doing the engine swap so I wouldn't run into any problems when I was done. (The compressor was not very old) The truck has been sitting for awhile, a little over a year now. Everything runs great just the a/c wont blow cold. I charged it up and the accumulator is FREEZING but only heat blows out of the vents on all settings. Not fun in Florida, especially with a 6 mo old. So I stuck my hand under the passengers side dash, way way back I feel cold cold air. Just don't know whats going on? Messed with some of those little round UFO looking diaphram things and nothing seems to work? Am I missing one? Any information would be greatly appreciated. Thanks guys!

Did some more searching on here and found the vent door actuator. How hard is this thing to change out? Anybody have any steps?

 

Here is a schematic of the system:


If the temp door actuator, or air mix door as it is called in the schematic above, is stuck in heat mode, it can cause the symptoms you are experiencing.

BTW, please edit your post to include additional information including other threads you have found and/or have questions about. It is better to ask in one thread than to ask the same or similar questions across multiple threads. A link to said threads in your discussion is best. Thanks!

 

Alright, the schematics make sense, question 2, is there any way to "quick fix" this? It was very very hot today and I have a 6 month old and a girlfriend who daily drives this... Anyway to rig it to where atleast a/c comes out? It looks as if I have to pull the whole dash to get to it Unless I am looking at the wrong thing? The Air mix door is the little electronically controlled square box ontop of the blower motor?

 

This can be replaced without pulling the dash, it is just a bit difficult. A low profile ratcheting screw driver will help get at the screws that hold it in. If that is the problem, then you may be able to remove it and lock it out of passing the air over the heater core.

 

Temporary Florida fix, popped the two screws out of the top of the electronic actuator (not easy, many little cuts) and then the big gear inside of it was cracked. Which was my problem, the actuator wouldn't grab the teeth on the door pin. I manually turned the flap and voila, freezing a/c. That's all I need for now lol. Will be hunting down a new actuator. Thanks guys!!!

 

Hopefully it stays there!

And there is another satisfied customer!!