cjb7804

Got a problem that I haven't been able to figure out. On my 2000 GT, when I run my AC and end up pulling a fairly long hill, the air ends up switching from the vents, to the defrost. So somewhere I'm loosing vacuum. I checked all my connections and all seem solid. I've checked my vacuum reservoir behind the glove box and it holds vacuum. I've replaced the AC/Vent/Defrost switch and that didn't make a difference.I'm not for sure what else to check from here. Does anyone else's car do this or have they had the same problem and fixed it. I'm stumped and not for sure where to check from here. Any help would be greatly appreciated.

blackstallion666

have you tried setting it the floor and seeing if it still switches. possibly the switch is bleeding off some of the vacuum.

cjb7804

It seems to do it only when it's on Max A/C. I just replaced the switch and it still did it. I'm starting to wonder if it could be the vacuum motor that runs the blend to blow out the vents and suck in on the defrost when on Max A/C. It is also kind of sporatic. It will do it sometimes and other times works perfect. I'll have to see if there is any other specific thing that causes it to do it.

blackstallion666

well aslong as you have a good vacuum to the control switch, and since you put in a new switch and say all the connections there are good. I would say your on the right path. Unless theres a small leak in the line to the actuator.

blackstallion666

Also if you have a hand vacuum pump. You can manually control the actuator. Apply vacuum to the line from the control switch and see if it bleeds down. It should hold vacuum if its working properly.

2012White5.0

Now Im not trying to sound stupid or anything like that. If I remember correctly when I took my radio bezel off and removed a vent b/c it wasnt moving that there is some sort of flap/door that seemed mechanical behind the dash that directs the air flow in the car. I couldnt figure out what it was as first until i turned on the car and started playing with the AC and found that if i turned it to blow out of the normal vents the flap would be opened up but if I turned it to blow out the defroster it would close. Maybe there is somthing going on with that flap and its falling closed when he goes up hill. The only reason Im throwing this out there is b/c cjb7804 said he cant seem to find any vacuum problems. Feel free to correct me if im wrong its just what I remember seeing a few months ago when I took apart, some of the dash and may be totally wrong.

cjb7804

Yep, thatvacuum motor is what i'm starting to expect. It controls the door inside the housing. I hadn't hooked up a vacuum pump tothe motoryet, but I was going to try that and see if the vacuum drops.