2002 Blazer I had the compressor fail last year near the end of summer so I just put up with no AC. I just replaced the compressor yesterday and it's cooling the line fine (the evaporator gets cold) it seems like the air from the AC is being sent through the heating core thus making the air hot before it makes it out of the vents. Any help would be greatly appreciated.

 

Check if the blend door actuator is working or not. It is the same actuator that controls the heat for heater system. So one way to test is to see if the temperature when in heat mode can be adjusted/changed. If not, do a visual inspection of the blend door actuator by watching if it can turn the door axle. You can do that by opening up the glove compartment all the way so that it swings down.

You also could have a vacuum problem, i.e. a leak in the hoses under the hood that supply vacuum to the vacuum door actuators.

This is the diagram from a 2000 with an auto climate control:




2000 Vac diagram for HVAC system

 

I looked into the glovebox cavity and it appears the plastic door arm for the actuator is broken leading to the actuator arm not moving it. I manually turned the door so that the end that connects to the actuator arm is facing to the driver's side and it feels a bit cool but not Max AC cool so it appears somewhere the air is still passing the heating core.

 

OK, that is a good start. The repair/replacement of the blend-door actuator is well documented in the forum and on-line, e.g. YouTube.

As for the "Max AC" setting, my understanding is that if you have the computer controlled HVAC system, the one where you set the temperature, you should be able to press a button on the HVAC control panel that opens a door also accessible behind the glove box (more up and to the right) that draws air in from the passenger compartment. If you don't have a computer controlled HVAC system, then "Max AC" is the setting that opens that door. Perhaps this door is not being opened?

I only have as a reference the diagram I included in the earlier post but I would guess that your system is similar. According to it, there is a "slave door" that should also close to isolate the heater core when the AC is in use. I guess there could be an issue with that door not closing however, with the blend door set to cold, if the slave door was set to warm, then there would be very little air getting through the system. How is the total air flow with the blower on max speed? If it is blowing well, then the slave door is at least not blocking the air flow.

I would also check the condition of the vacuum lines in the engine compartment that supply the vacuum to the front axle engagement cable and to the HVAC vacuum actuators. There could be a problem with a vacuum leak preventing a vacuum actuator from fully opening or closing.

 

The Max AC actuator and door work fine, I was just trying to say that it is nowhere near as cold as it should be. As far as I can tell the air flow seems to be okay but I really am not sure where that air temperature door is located. Is there a way I can manually turn the arm like I did with the defroster(?) door?

 

Do you have the Computer Climate Control system or the manual one? I ask as if you have the computer one, there is an access panel at the top, and to one side of the box that encloses the AC evaporator. (See the picture below.) Removing this panel gives you access to the blend door that then can be manually moved from there.

However, I believe the axle for the blend door can also be moved by reaching in from the glove compartment. Check out this video on how to replace the blend-door actuator. This should explain it all better than I could with only text.




The access door is circled in red and the top of the evaporator is indicated in green. The view is looking back towards the fire-wall on the passenger side.



The evaporator is on the left and the heater core is in the upper center part of the picture. The blend door is identified with the cyan arrow and the pivot axle for the blend door is identified with the yellow line.

 

I'll have to take a look at the video when I'm off from work. I believe it's a manual climate control since the middle **** only has the colors rather than numbers(?). It doesn't look like I can just unscrew that door next to the core like in the picture you provided. I assume I'd have to cut it with a utility knife since "cut here" or w/e is printed into the plastic.

 

The computer controlled hvac system is the one in the video. Yes, you might have to cut the panel out to gain access to the blend door. But you should see if you can move it by reaching in from the glove compartment.

Good Luck