AC and heat stop blowing at freeway speeds(sometimes)

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Jul 12, 2019 | 07:21 PM

holycaveman

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CF Veteran

Joined: Dec 2011

Posts: 3,643

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AC and heat stop blowing at freeway speeds(sometimes)

Pretty much as it says. Works great 90% of the time in town. When I drive for 20min or so on the interstate air stops blowing out of the vents. Fan works perfectly and no its not backwards. Sometimes its working on the interstate until I go up a hill then it stops blowing. My first thought was vacuum? So I checked all the lines in the engine compartment. They are fine. Anyone have this problem? Thanks 04 Grand Cherokee limited

Last edited by holycaveman; Jul 12, 2019 at 07:25 PM.

Jul 14, 2019 | 11:08 PM

dave1123

Old fart with a wrench

Joined: Nov 2010

Posts: 14,398

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From: Manlius, east of Syracuse, NY

Year: 2000 XJ Sport & WJ Laredo

Model: Grand Cherokee (WJ)

Engine: 4.0L

I'm assuming being a Limited, it's got the automatic climate control, right? That's quite a complicated unit and it actually has it's own computer and diagnostic system. There is a procedure on how to bring up it's trouble codes, but I don't have that unit, so I'm not familiar with fixing it. I'm sure it's in the FSM if you care to find out.

That unit is so complicated it has temperature sensors in various places inside the cabin!