97 Pontiac Montana Transport AC

I just inherited a 1997 Pontiac Montana Transport. Problem is the AC was repaired a while ago but now when you turn on the fan, nothing comes out of the vents. The fan is making the normal noise like it should be blowing hard, but nothing comes out of any of the vents. I was told by the previous owner that the mechanic came back and said that it was a simple connection in the engine compartment but they could not remember what it was. Any ideas? Any help would be much appreciated.

 

I am not sure if that year has a cabin air filter, but they will definitely cause the problem you are having if they get clogged up and are not changed. Check the owners manual to see if your vehicle has one and how to change it, usually pretty easy on G.M. vehicles. If not, there are "blend doors" inside the dash of the vehicle that direct the air flow corresponding to the selector position (i.e. defrost, floor, etc...). These are sometimes cable operated and sometimes vacuum operated, but most late model vehicles are controlled by a "control head" in the dash, that is what all of your knobs are on. Sorry I can't tell you much more than that. You might get lucky with the filter !!

 

Check to see if the fan blows air out the defrost vents..........If so, you have a vacuum control problem. In the engine compartment is a vacuum reserve ball somewhere in the front by the wheel wells........and a series of hoses that lead to the intake and into the passenger compartment.........Also a 1 way check valve so that the door position doesn't change when you put your foot deep in the gas pedal............Now you need to find the leak, good luck

 

Ok, thanks for the help. However, it isn't blowing anywhere. The rear air system works but isn't blowing cold air, I assume it is because the main system can't blow cold air. Any more hints?

 

If you can hear the front fan and cant feel any air flow something is blocking the main vent, but if you feel it on the floor and defrost then a vacum line is disconected. with the motor running listen under the hood for a small>med. hissing/sucking noise, this will lead you to the hose.
The rear ac wont blow cold unless you have the ac on at the front 1 compressor does front and back.

 

1997 to 2000 Transports did come from the factory with a a cabin air filter. This does not necessarily mean that YOUR Transport has one. If it does and it is clogged up, it will prevent air from flowing through the vents. The filter is located in the glove box. Procedure for changing is:

1. Open glovebox and remove cover at the
back of the glovebox.
2. Unlatch door to vent filters.
3. Remove filter that is visible. Another filter is
located along side (left) the one just
removed. Slide it to the opening and remove.
4. Slide in (2) new filters and close door.
Replace cover at the back of the glovebox.

The ATP part # is GA-2 if you need one.

If you do not have a cabin air filter and the fan is blowing, you have a blend door problem.

 

Ok, Thanks again for all the ideas. Here is what I have so far. Changed the inner cabin filters with the first post, nasty dirty but did not change anything. Air blows out the bottom but NOT the vents or defrost. I can hear the fan blowing like it should be chilling up a storm and I can feel some coldness coming from the vent but no air is moving.

I certainly appreciate all the assistance and any additional ideas are certainly welcome. From what I can take from your previous posts, it sounds like a vacuum issue but I am confused because everyone says that would be the case if my defrost is blowing out which it isn't. Any thoughts. Thanks