I have been trying to figure out my blower air movement issue on my 89 for a while. On max ac with the fan full it is like the low setting on any car. Nice and cool but just no air movement. I thought it was a weak blower so I replaced it. I cleaned the evaporator, and put a new heater core in. I cleaned up and made sure the vacuum controller was in good shape. No leaks and it shifts vents just like it should. I attributed it to something getting disconnected behind the dash from when I pulled the dash out a few years ago.

I got thinking in my head what about the input to the the evaporator under the windshield wipers/cowl, and imagined there was a bunch of leaves down there.. I just took the windshield wiper and cowl plastic off and felt around in there. It just seems like a big hole that feeds into the blower area. I flipped on the blower just to see what was happening and boom a bunch of air started flowing out from the cowl area. As I understand that is supposed to be an input not output area. This must be where my extra airflow/ac is going, straight out the cowl. I was thinking the blower was backwards but I still get some air moving in the interior. What else could this be? Do I have a broken door somewhere? Please help.

i searched TGO for this problem and couldn't find anything. I do remember reading a thread some years ago about a blower door that needed to be taped up to increase airflow, but haven't been able to find it since then.

 

cage fans can back flow some but that does sound odd.

On Max AC that should pull from the inside of the car, bi-level pulls from outside. If its pulling from the inside but not closing off the outside port I could see that happening.

You can find exploded diagrams on gmpartsdirect.com that may help:

https://www.gmpartsdirect.com/auto-p...umber=19131214

 

https://www.gmpartsdirect.com/auto-p...omponents-scat

I would look at 5-8 and 14 on this diagram and see.

Item 5 I believe is a big block of foam if that has turned to dust it could cause this.

 

Thanks Aviator, awesome diagrams, I didn't even think to look for parts pictures. I figured there was a flap down there somewhere.

I started the car and ran it through max, and norm and vent. This flap didn't move from this position at all, and the air continued to blow out from the cowl. I guess there is an actuator somewhere and this foam may potentially be the problem, looks like I will be taking the dash apart afterall.

 

Of course these parts are not available new, the foam and rubber seals can be cut at home.

If you take it apart I would buy some foam stripping at hardware store as alot of the ducts use this at connections.

I suppose you Could pull that flap up manually with a strong magnet on a rope to see if it helps

 

Thanks again for your help, found out the actuator you can get to from under the pass kick panel, comes out by loosening 2 10 mm nuts.

Do you think this has anything to do with it? The actuator I pulled out.

About 5 years ago when I was installing the sub frame connectors the interior caught fire. I put it out quickly with a fire extinguisher, but apparently this melted. I guess I have had a vacuum leak all these years. SMH

Thanks for your help, hopefully this permanently fixes it, now to find a new one.

 

Lol yep. eBay junkyard or Hawks is best bet. I think there are vacuum actuator rebuilders also.

 

If you don’t mind a used one check with @beths91camaro

 

I do have those actuator pieces in good shape.
Thanks for the recommend, tuned.