1997 Jeep Wrangler Defroster Not Switching

1997 JEEP WRANGLER
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FXDL2003
  • MEMBER
  • 3 POSTS
We have a '97 Wrangler and the defroster does not work. The heater kicks @#$ on the floor and dash. But when we switch it to defroster it does not switch to the windshield vent. The defroster vents for the passenger/diver windows work. Is there a way to check this and repair it?

Thanks,
Andy
Dec 10, 2006 at 1:21 AM
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CARUNDELL
  • ✓Experienced Mechanic
  • 602 POSTS
[quote:dd5eda7f8c="FXDL2003"]We have a '97 Wrangler and the defroster does not work. The heater kicks @#$ on the floor and dash. But when we switch it to defroster it does not switch to the windshield vent. The defroster vents for the passenger/diver windows work. Is there a way to check this and repair it?

Thanks,
Andy[/quote:dd5eda7f8c]

Hey andy,
The heater/defrost control "doors" are controlled by vacuum, check under the hood and find the small vacuum line that goes thru the firewall and make sure its attached to a vacuum riser on the motor. Check under dash at or around the heater box for broken or disconnected vacuum lines. Hope this helps!

Regards,

Chris
Dec 11, 2006 at 3:01 AM
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FXDL2003
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  • 3 POSTS
Thanks, I had the control unit out and noticed all the vacum lines were attached, I did not check at the engine and firewall. Thanks for the tip. I'll check this out soon.

Andy
Dec 11, 2006 at 10:31 AM
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Suggested Repair

The heater and defrost mode doors are vacuum-operated. Check the small vacuum line under the hood that passes through the firewall and confirm it is connected to a vacuum source on the engine. Also inspect the vacuum lines under the dash at the heater box for breaks or disconnections.

Conversation Summary

The owner of a 1997 Jeep Wrangler reported that the heater works on the floor and dash, but switching to defrost does not direct air to the windshield. Side-window defroster vents still work. An expert explained that the mode doors are vacuum-controlled and advised checking the vacuum line from the engine through the firewall and the lines at the heater box. The owner had already confirmed the lines at the control unit were attached and planned to check the engine and firewall connections.

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