all fan speeds work but won't switch from floor to defroster outlets.
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2002 Oldsmobile Alero Question: why won't blower fan blow out defrosters ?
Answer #1goodguy November 14, 2013, 20:40Master
check your blend door actuator
Answer #2csubak30 November 14, 2013, 22:31Master
If this vehicle has a vacuum harness to the vent control system, follow the line through the firewall to the vacuum pump and make sure there are no breaks in the line. You will know from past experience if it was a vacuum setup by when you adjusted the direction you probably heard an 'air slurp' as you switched from floor to defrost etc.
Answer #3cardocIII from Gillespie's Auto Service, November 15, 2013, 01:51Master
When you select defrost vacuum should be applied to the blue vacuum line which pushes the defrost door open and the heater door closed, and the red vacuum line which closes off the dash vents.
Greg's Orange Auto (13199 Answers) , Orange, CA - (714) 361-9386globalhelper November 15, 2013, 06:07Master
agree with #1
Answer #5G. T. Service Center (4142 Answers) , Stephenville, TX - (254) 638-3236ProfessorG November 15, 2013, 06:59Master
The defrost door is operated by the Red & Yellow vacuum lines, Per 'Mitchell'. The Blue & Green operate the Mode door which closes the vents. Don't agree with blend door, unless you have a heating issue.