it was the first time of the year i tried the ac. worked great. however, when the ac is on what ever setting its on it does that and defroster and floor...i know what you're thinking ...another blend door problem...but heres the twist...when on heat, the floor, floor/defrost, and vents all work perfectly and does not come out another vent then the one its set on

any help would be great, thanks in advance!

i have a manual, not autoclimate or whatever you call it lol.

also when set on ac or max ac....which vents is it supposed to come out of? just the 4 front ones?

 

When MAX AC is selected, three actuators get vacuum. When HEAT is selected, only one actuator gets vacuum. When BLEND, (floor & windshield) is selected, none get vacuum, I'll bet that one works great. My guess is you've got a vacuum leak, insufficient vacuum to the system. Check the lines under the hood first. If no problems there, start looking under the dash. A hand vacuum pump would be a good choice here

 

Thank you captain! With the vacuum lines under the hood, i replaced a bunch of the ones on the drivers side last spring including all them that go to the t over the brake booster. Is it possible it could be the lines running off the 4wd actuator? (4 button) that run below the battery tray .....4wd and cruise work fine

 

Cruise is all electric, so that can't be the problem. 4WD actuator under the battery tray only gets vacuum in 4WD, so that can't be the problem unless it happens only when 4WD is selected. If the vacuum source line going to the vacuum switch on the transfer case leaks, or the vacuum switch itself, or the vacuum reservoir leaks, or any of the vacuum lines or actuators in the dash leak, any of those could be the problem.

 

Visually speaking....under the hood looks good...the only one that looks bad is the one that goes under the battery tray but thatll be done this spring. To get to the actuator, do i just take the glove box off? I know theres something by the gas door i assume thats for the blend door?

 

Gas pedal**** not door lol

 

There are 3 vacuum actuators under the dash, and one of them has two diaphragms. Two of the actuators are above, and to the right of the gas pedal. The third actuator is under the dash, extreme right side, above passengers feet. One of these things will pinpoint the problem in a matter of minutes: Brake Bleeder and Vacuum Pump Kit Not professional quality, but it will do the job.

 

Assuming under the hoods fine, i notice theres atleast 4 different colored vacuum lines....red blue and brown yellow...is there any i can eliminate as the culprit based on my problem?

Im not gonna be able to get my tools until next week so im tryna learn as much as i can so im set for when i take a look
Also what size/type of vacuum line is used on the dash

 

What year is the vehicle?
Does the four-wheel-drive switch on the dash have three buttons or four?
In the max AC position, airflow should only come out of the dashboard registers. Also, in the max AC position, the actuator behind the glove box has an orange vacuum line. It should only have vacuum in the max AC position.
A hand vacuum pump will make diagnosis quick and easy.

 

2000 and a 4 button. Gonna have to pick one up at hf this weekend