2000 Jeep Cherokee stuck in defrost mode

Tiny
PAM SMAWLEY
  • MEMBER
  • 2000 JEEP CHEROKEE
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 17,700 MILES
This is a right hand drive jeep I use to deliver mail in, recently the air conditioning only comes out of the defrost vents and actually the heat as well. My husband took apart the dash to try to fix it, but was unable to see where the vacuum system was. We need a diagram of the vent system in order to fix what seems to be stuck shut. Sometimes the fan won't work at all, then if I hit a bump it will come back on
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Saturday, September 5th, 2009 AT 2:15 PM

5 Replies

Tiny
MERLIN2021
  • EXPERT
This sounds like the vacuum supply line is either broken, or the reserve tank is checked that supplies vacuum during periods of low vacuum(accelleration.)


http://www.2carpros.com/forum/automotive_pictures/62217_jeep1_2.jpg



http://www.2carpros.com/forum/automotive_pictures/62217_jeep2_2.jpg


Recheck the electrical connectors for the fan problem!
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Saturday, September 5th, 2009 AT 2:44 PM
Tiny
PAM SMAWLEY
  • MEMBER
Where do we find the junction box in the diagram?
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Sunday, September 6th, 2009 AT 10:29 AM
Tiny
MERLIN2021
  • EXPERT
This diagram shows when vacuum is applied to which setting. Your problem is the supply line(black) vacuum hose comming in from the firewall. Or the reserve tank, both are under the hood, the supply line comes from the intake manifold on the top of the engine, goes to a check valve then to the reserve tank, and into the control head inside the car. This or the control head is the problem, do you have a vacuum tester? It's a hand held pump with a vacuum gauge on it. Attach it to where the black supply line is, pump it up to 18-22 hg, system should now switch to any desired airflow output, if not the control head is NG!
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Sunday, September 6th, 2009 AT 9:36 PM
Tiny
PAM SMAWLEY
  • MEMBER
Just want to thank you for your prompt and informative answers, can you tell us where the control head is,
thanks again
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Monday, September 7th, 2009 AT 5:32 PM
Tiny
MERLIN2021
  • EXPERT
Thats the selector switch.
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Tuesday, September 8th, 2009 AT 6:12 AM

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