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Heater not working

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Joined: 23 Oct 2006

PostPosted: Mon Oct 23, 2006 8:53 pm    Post subject: Heater not working Reply with quote

I recently changed out the heater core and the air conditioning evaporator core on my 1995 Jeep Grand Cherokee. Although the input and output heater core hoses are hot, there is no heat inside the vehicle. I've checked all of the vacuum operated "motors" that opens the doors to the air box and they all work fine. I noticed that the temperature control knob has an electrical output. Does anyone know how this works? Could it possibly be an electrical problem that is keep the heat from coming into the cab? Does one of these "motors" operate a door that allows heat to exit the air box? Thanks in advance for your help.
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Joined: 13 Sep 2005
Location: New Hampshire

PostPosted: Tue Oct 24, 2006 6:47 am    Post subject: heater Reply with quote

This post should be in the Grand Cherokee forum. I think the temperature is controlled by a motor that moves a flapper door. My manual doesn't show much detail in this area. Look under the dash for any arms that look to connect to motors, if you listen under the dash with the key on but engine off you can usually hear it as the temp knob is moved. I would guess yours is jammed or not connected seeing it has been worked on recently.

Present: 99 Cherokee
Past: 86, 87 Cherokee; 94 Grand Cherokee
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Joined: 27 Aug 2006

PostPosted: Sun Oct 29, 2006 6:01 pm    Post subject: Reply with quote

If the core was bad due to corosion then the valve that opens the bypass may be sticking find it and actuate it by hand see if it is real stiff or struck. That will usually do the trick by freeing it up or you will know it needs to be replaced. It will have a small arm or maybe electric if electric clean the plug whith a Qtip put some light grease on it prongs plug it back in. GB brand electrical anti corosive grease is sold at Home Depot where they have the wire ties and that sort of thing good stuff for any electrical connection because it is also conductive. Great for trailer plugs.
2005 Grand Cherokee ,white,V6 Stock but fun and great ride.
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