1994 grand Cherokee
Air does blow a/c is cold all that works, but as soon as you put it on recirculate it actually blows less and you can hear the door opening for the vent, fan increases speed but actually slows the air blowing out.
I know 99-04 had issues but i cant find anything on this 94 of any value - i do not know of any air leaks and air does not blow out of other vents
That is not a blend door issue The blend door mixes hot and cold air. Then there are two mode doors for controlling direction of air flow, and there is a recirculate door for controlling outside air. It sounds like something is not functioning with the recirculate door. You can pull the glovebox and watch the door move and see if there is anything wrong.
The variables during the different modes assuming the vehicle is moving are: 1. Air velocity supplied to the fan. In recirculate, the fan has no positive pressure driving it so the volume is reduced. There is no attempt to pressurize the cabin so besides the resistance of coils or ducts {which is constant in either mode} the fan freewheels to a point so speed increases,but without positive pressure the volume does not. 2. Air velocity supplied to the fan. In other modes air is taken from the cowl which utilizes air pushed into the fan plenum and acts as a booster in volume. The fan is running slower because it is attempting to pressurize the cabin but the air flow is stronger because of positive pressure. The exhauster vents prevents this from becoming a real issue.
I have no idea if this is actually what happens but thinking it through, it makes sense.
My guess is that the recirc door isn't opening properly. Mine suffered from a faulty actuator (twice) and in the end I replaced it with a mechanical control in the form of a modified choke (strangler) cable. It's fine now
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