Draft through vents while driving

ZappyBear

Member
I'm lost on how to fix this. I get a draft through whatever vents I've selected while driving on the road and the fan turned off. It becomes noticeable around 40mph and very noticeable at 55 and it doesn't matter if I have the AC on or off. It's very annoying and would like to get it fixed while I've got the tranny out so I can make a mess while I already have one.
 
I would be checking the blend door / actuator servo to ensure that is operating properly. If that checks out, I would be looking for a hole in the A/C housing under the hood.
 
Already checked for cracks and holes on anything plastic under the hood. No unwanted holes or cracks. I will check the blend doors when the weather lets up, I'll give the blend doors a check. Do they have foam seals around the edges like the gmc s15's blend doors did?
 
There is only one blend door. It is located to the right of the radio and left of the glove box. Easy way to check if it is functioning correctly is to turn the blower on and change from heat to defrost to vent, etc. If the air blows ANYWHERE but where it should, then you have a problem (either the actuator or the door itself. Depending on the model year, it could be electric or manual (cable operated).
 
There is only one blend door. It is located to the right of the radio and left of the glove box. Easy way to check if it is functioning correctly is to turn the blower on and change from heat to defrost to vent, etc. If the air blows ANYWHERE but where it should, then you have a problem (either the actuator or the door itself. Depending on the model year, it could be electric or manual (cable operated).
It's cable operated, I thought it would have 2 doors. 1 for determining vent, floor, and defrost, and another one that switches between covering up the heater core, or evaporator. My issue isn't air going the wrong direction, it's air coming out of the vents when driving and everything on the environmental controls turned off. I've already confirmed the blower receives no power when in the off position.
 
Sounds like the servo that directs the air for the vents is not closing all the way. Those, BTW, are not blend doors as they don't blend hot and cold air to achieve the desired temp.
 
Sounds like the servo that directs the air for the vents is not closing all the way. Those, BTW, are not blend doors as they don't blend hot and cold air to achieve the desired temp.
Thanks, I'll try to get it checked out this weekend when it's warmer. Should I be looking right where the heater core is, or is it a little further down?
 
In know there is one at the lower right side of the dash. Not sure where the others are (I believe there is more than one).
 
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