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05 Nav. Blend Door Issue AC

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So I have been having this issue that seems common amongst the Navigators. Every now and then the AC will stop blowing through the main AC vents and only comes out cold through the defrost top vents. From what I can see under the hood is a vacuum line that goes to this actuator (see pics) that controls the blend door. - I think? The vacuum tube from the actuator heads into the firewall. so I can't see beyond that. I noticed that when I start up the Nav and have my AC on, the rod attached to the actuator will close, and I will get cold air blowing from the main vents.

When the cold air blows only through he defrost vents I noticed that the rod attached to the actuator will remain open. ( see pics)

Do you think I should replace this vacuum actuator since I can see much beyond this?. I don't see any cracks on the vacuum line in the engine compartment.



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Posted (edited)

The vacuum system is made of the EATC control head, the lines, a check valve near the engine, a reservoir and door vacuum servos for the mode (floor, defrost,vent), recirculation door and the water shutoff. 


That is the water shutoff, not a blend door. In MAX AC vacuum is supplied to the recirculation door in the cabin and to the water valve in addition to the mode door to move it to VENT. What you are seeing in the valve is a symptom, most likely. IF you think it is the valve, just plug the vacuum line with a golf tee and retest. 

You have a vacuum leak or a failure of the vacuum control part of the EATC.  


The blend door, which sets the temp of the air, is controlled by an electric motor. 

Edited by YT90SC

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