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2001 Mazda Tribute Blend Door

Problem 
1K views 5 replies 3 participants last post by  dwightbresemann 
#1 ·
blend Door is not changing from defrost to vents. I know this is a vacuum problem but does anybody have any idea of where to start looking
 
#2 ·
The mode door changes the selection of the outflow from the HVAC. It is likely a stepper motor or cable, I think. The blend door 'blends' cooled air and heated air to select the temperature. Unless you have the system with individual controls for driver and front seat passenger, there is only one blend door. The 07 in my garage uses a stepper(I think) to change the temperature. The control feels as if it is not doing anything as you move it back and forth, so I expect limited mechanical work being done.
I would look at the control head with the fan, mode and temperature settings before digging deeper. Ford did have a lot of failures with their HVAC design that caused broken hinges when the stepper motor went full-tilt in one direction to determine its position(every time... when key ON). There are other posts on site.
tom
 
#5 ·
If all you get is DEFROST mode, then there is little to no vacuum to the defrost panel operator. The default mode is DEFROST, so if you have a failure it will clear the windshield. The other two vacuum operators direct flow to the panel and floor.
The vacuum source could be missing, the tubes broken or loose. The switch that changes in the control head could be leaky, causing low vacuum, enough to leave it in DEFROST no matter what you select.
There is a multi-line connector shown in the imaged Dwight posted. That will be behind the control head. I would check that it is intact. I would listen for vacuum leaks behind the controls/radio. I would check the vacuum line from the intake manifold under hood is connected tightly and intact.
There should be a vacuum diagram of all connections and routing on the radiator support. Check them all, as reduced vacuum from 'something else' also reduces vacuum available to operate the vacuum 'motors'.
tom
 
#6 ·
If all you get is DEFROST mode, then there is little to no vacuum to the defrost panel operator. The default mode is DEFROST, so if you have a failure it will clear the windshield. The other two vacuum operators direct flow to the panel and floor.
The vacuum source could be missing, the tubes broken or loose. The switch that changes in the control head could be leaky, causing low vacuum, enough to leave it in DEFROST no matter what you select.
There is a multi-line connector shown in the imaged Dwight posted. That will be behind the control head. I would check that it is intact. I would listen for vacuum leaks behind the controls/radio. I would check the vacuum line from the intake manifold under hood is connected tightly and intact.
There should be a vacuum diagram of all connections and routing on the radiator support. Check them all, as reduced vacuum from 'something else' also reduces vacuum available to operate the vacuum 'motors'.
tom
Tomw, good, accurate information. A figure of the function switch, located on the back of the panel.

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