Auto Air Conditioning & Heater Repair: Blend door not working, oldsmobile cutlass supreme, oldsmobile cutlass

Question
QUESTION: How can I troubleshoot the blend door on a 1997 Oldsmobile Cutlass Supreme which is stuck in the defrost position? It will not operate when you turn the switch. Is there a fuse or could the switch be bad?

ANSWER: Hi David

Need to know if automatic temp. control or manual.  If manual check your vacuum lines and make sure they are good.  If ATC then check if you have problems on other doors or just that one.  If only there then go to the actuator motor and check for power and function.

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QUESTION: It's a manual switch. The vacuum lines going to the actuators (there are 2 ) appear to be in good shape and so do the lines that go to a junction (?) box. I guess this is where it gets the vacuum from. What creates the vacuum?

Answer
Hi David

Pull one of the vacuum lines see if you have vacuum.  If you don't have vacuum look in engine compartment on drivers side fire wall for a loose line if all lines are connected make sure they have vacuum.  If you don't  look around the rear of engine for broken hose.  If you have vacuum look near and underneath the air filter for a broken hose.