I will check it out later and let you know the progress. I know I have to remove the blower anyway because it is starting to get a little noisy. I will check the evaporator then. Tks. for your help. I did however get warm air to come through the defroster. I took the blend door motor off beside the gas pedal and manually turned the leaver to another position but cannot get it to blow through the vents yet. I am suspecting that there is a problem slightly beyond the leaver. The linkage seems to be okay but will also try and check that out. Just wish there was more room under there. And if wishes were horses, I suppose we would all be riding instead of walking. Talk at ya later.
Ray

 

Mr Shamrock, I have an 89, 1500, silverado. Cold air is coming in through the heater duct when going down the road with all the controls for the heat/air turned off. I think one of the outside air vents is staying open. I see the one over on the right side behind the blower motor for the fresh air/recirculate. Dont know if its working right. Where is the other vent door located? And how do you get to it? How do you replace the servo for the one behind the blower motor? Thanks, Roger, in Spartanburg.

 

Yes the one you see that is nearest the blower motor (towards the fire wall) is the one that causes your issue. I would look to see if it is moving when you adjust the controls for recirculated air. In my 89 GMC I used to drive I just put the door in the closed position and unplugged the motor. You won't have an outside air option, but I didn't care about smelling the guy in front me exhaust anyway. If you want it fixed you either have - a bad motor, stuck door, or bad control head. Start by seeing if the motor is turning when the control panel is adjusted - it may turn but have a stripped gear so it won't close. Next remove the motor and see if you can turn the shaft that it was removed from by hand. It might just be stuck and need a little persuading to start opening and shutting. If it is hard or won't turn at all remove the blower motor and look inside the plenum and work the door back and forth to free it up. Once it is moving easily then you can address whether the motor is good and/or if the control panel is doing its job. To save a little on a stripped motor gear take the motor apart, remove the gear and put it back on 180 degrees from how it was previously mounted. Since the motor only uses a portion of its gear you can turn it to where the good unused teeth are instead of replacing it. Good luck!

 

I had to replace the blower motor a while back. The door was closed. a put a stick in there to hold it closed. Still getting cold air. Where is the servo motor for it located? Is there another vent that lets outside air in? If so how do you get to it? Thanks, Roger.

 

Thats the only place that I am aware of that would allow fresh air in. The servo motor is directly behind the blower, but up in the dash a little (so a little higher and behind the blower). It is the same type motor for the other blend controls. I would pull the blower to make sure the stick you put in there hadn't fallen.

 

The door behind the blower is closed,stick is in place. Cold air still coming in. Dont know from where.

 

When you say it is closed it is in the up or down position? It should be in the up position blocking outside air and allowing the air to be taken in from the cab. The only other place cold air could come in from would either be around the evaporator or heater core connection pipes. Unless you have some other non-A/C leak like the antennae wire boot/plug or a harness that passes through the firewall. Is it a lot of air? Does it come in with the blower off?

 

It is in the up position. After I scotched it in the up position, Air started coming in through the air return below the blower. Its strange I know. Its alot of air. Enough to blow empty plastic grocery bags around. Everything is turned off. The faster you go the more air. Maybe I dont have the door closed all the way. It sure looks like it though. Whats the best way to take that servo off ? Take the glove box out? It looks like its between a rock and another rock. Not a rock and a hard place.

 

Sorry to highjack. My 95 is giving me greif. Htr fan was only working on top speed. Changed resistor and all speeds worked for a day then back to high only. Changed blower motor and resistor this time and still only high speed. Whats left...switch? any suggestions. tnx.