Join Date: Sep 2007
Location: Dallas Texas
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Heater/AC vent control switch vacuum leak
So there I was driving down the road and I noticed it was a little warm inside the cab...I turned the vent control knob to max ac and heard a vacuum leak. When I got home I pulled the panel off and it sounded like the switch was leaking....so today I replaced it. New switch leaks just like the old switch...so I replaced it again with another new switch from Ford and the second switch has the same issue.
Since its not the switch....what could it be? It leaks on max AC and defrost, I cant seem to locate any vacuum diagrams and not sure where the lines run too and I couldnt find the vacuum solenoid that should control the air recirculation for the max ac and defrost.
To troubleshoot so far - I ran some short 1ft vacuum line by plugging them into the silicone harness that connects into the back of the switch and jumpered them from the center port where the vacuum supply is and put them to each port manually and there were no leaks. The vents seemed to move through from defrost to vent to floor as it should. I couldnt find the recirculation vacuum solenoid but didnt hear a leak when messing around with the jumper. So the lines themsleves arent leaking and hold vacuum. I also ran some grease around the vacuum connector and it still leaks so I am confused on what the issue is.
Thanks in advance.