Question about 2004 Jeep Grand Cherokee

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"the a/c will go to defrost outlets when the engine is under load going up a hill what can cause this"

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You are loosing vacuum to the dash control. There should be a one way vacuum check valve under the hood that feeds the dash control. Change it, it is bad. I would have to look up the exact location but it is in the vac line either on the intake or brake booster.

Posted on May 09, 2009

  • Clint Smock
    Clint Smock May 09, 2009

    You are loosing vacuum to the dash control. There should be a one way vacuum check valve under the hood that feeds the dash control. Change it, it is bad. I would have to look up the exact location but it is in the vac line either on the intake or brake booster.

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  • Jeep Master
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Sounds like a vacuum problem.the position actuator is driven by vacuum.
going up a hill decreases the manifold vacuum and may do that type of thing.
some vehicles have an a/c compressor override under hard acceleration.vw and saab to name a couple.

Posted on May 09, 2009

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