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I cannot get my car to blow anywhere but in the defrost mode…

Customer Question
I believe my mode door...
I believe my mode door is stuck because I cannot get my car to blow anywhere but in the defrost mode. It used be be sporadic but now it is that way all the time no matter what position I put the mode knob in. Can you help?

I have checked the vacuum hose under the hood and it is connected properly.
Submitted: 8 years ago.Category: Jeep
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Answered in 1 hour by:
6/22/2010
Jeep Mechanic: Ricardo Hohl, Master Certified Tech replied 8 years ago
Ricardo Hohl
Ricardo Hohl, Master Certified Tech
Category: Jeep
Satisfied Customers: 4,343
Experience: Automotive instructor at Porter and Chester institute
Verified
hi if the mode door was the problem you would still have level controls they are individually control by the climate control and is control by vacuum and a vacuum distributor behind the climate control, have you been doing anything around the climate control like a radio ? you say the main vacuum outside at the engine compartment is ok? have you follow the vacuum from the vacuum source and in to the fire wall outside the engine compartment?

Edited by ricardo hohl on 6/22/2010 at 4:11 AM EST
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Customer reply replied 8 years ago
hi I have not been doing anything around the radio. Is this total vacuum control or is there a motor or something acuating as well? Occasionally it will blow out the front vents on its own when I have it set there to recirculate or one of the front settings. Where is the climate control? Should I look for a loose hose under the dash or something? Also, I followed the tube from the intake all the way to the firewall and found no apparent damage.
Jeep Mechanic: Ricardo Hohl, Master Certified Tech replied 8 years ago
good morning, the vacuum house goes from the intake to the fire wall and from there to the climate control head (this is the control in the center panel itself),the vacuum connects to the back of this controls and is distributed by a vacuum distributor with in the control head, as you move the knobs the vacuum is send to that door actuator and the actuator is connected to the door that opens and closes the air passage to the level on demand, you say none of the levels work but you have vacuum all the way to the fire wall, now we need to remove the control head to see if the vacuum is getting to the c/head from the fire wall, if vacuum is getting to the head then the problem is the control head, if vacuum gets to the head and some of the vents other then upper windshield works then you have a vacuum door module at that door level leaking vacuum, go under the dash and see if you see anything out of place and let me know.
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Customer reply replied 8 years ago
thank you ...I will check that. None of the other vents other than windshield work. I will check the control head.
Jeep Mechanic: Ricardo Hohl, Master Certified Tech replied 8 years ago
ok let me know what you find.
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Customer reply replied 8 years ago

I have been busy at work and will try to check the control head tomorrow. Can I disconnect the input vacuum line with the car running and feel the vacuum suction? Is this how I know I am getting the correct vacuum from the intake manifold (I believe this is where it comes from?)

Jeff

Jeep Mechanic: Ricardo Hohl, Master Certified Tech replied 8 years ago
yes disconnect the hose and check for vacuum., i will be on line tonight if you are ok, and if not then tomorrow.
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Customer reply replied 8 years ago
sorry for not getting back to you. I have been out of town (without the Jeep). Last night I messed around with the mode control again. One thing I noticed was that when I moved the control to recirculate, I could definitely hear the sound of the air flow change (still coming from defrost vents though). I believe the recirc door is actuating but the air still comes from the defrost. Is this possible? Maybe the mode control is partially functioning or maybe I have another actuator messed up? Sorry for asking so many questions.
Jeep Mechanic: Ricardo Hohl, Master Certified Tech replied 8 years ago
that is because you are loosing vacum to the mode door and this can be the control head or the mode door actuator. you still need to remove the control head and check the back for vacumm leaks.with the engine runing. when you press resirculate you are opening the resirculation door this is not the mode door.
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