Blend door, heater core, or what???? - Jeeps Canada - Jeep Forums

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Blend door, heater core, or what????

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Old 08-25-2010, 05:51 PM
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Canada Blend door, heater core, or what????

Hey Guys, I have a 2002 Jeep Grand Cherokee Ltd, when i bought it i thought the heater core was shot, when i'd run the heat steam would come from below the glovebox, but now (a few months later) when i try the heat I just get cold air, the A/C works fine, and i appear to be leaking coolant from my overflow, but not inside the jeep, any help would be greatly appreciated
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Old 08-25-2010, 07:54 PM
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Default Re: Blend door, heater core, or what????

Steam coming out from under the glovebox is usually a good indicator that you have a problem with the heater core or a major leak under the hood. Is the coolant coming out of the resevoir while it's running or after you shut it off?
#1 Check the thermostat, if it's gradually doing it while it's running then I would suspect that you may have a head gasket either going or it's already toast. If afterwards I'd start with checking the thermostat and the waterpump for circulation.
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Old 08-28-2010, 01:20 PM
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Default Re: Blend door, heater core, or what????

Ok, here's the latest update now when I run the heat the Ac compressor kicks on and the overflow bottle starts pumping coolant onto the street. The jeep doesn't overheat and the level in the rad is unchanged, Please help!
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Old 08-28-2010, 01:49 PM
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Default Re: Blend door, heater core, or what????

Well the A/C and the overflow aren't connected, the A/C is a sealed/ pressurized system seperate from the heating system.
If your pumping out coolant and the rad isn't going down then I would change the thermostat and check to see if the rad is plugged up. Are you running HOAT (orange/ pink) in your rad or something like Prestone (green)?
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Old 08-28-2010, 01:57 PM
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Default Re: Blend door, heater core, or what????

I'm running prestone green, the level In my overflow tank keeps dropping, but not in the rad,
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Old 08-28-2010, 03:41 PM
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Default Re: Blend door, heater core, or what????

change the rad cap. sounds like it's not holding jpressure.
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Old 08-28-2010, 06:35 PM
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Default Re: Blend door, heater core, or what????

Doh!!! Completely missed the most obvious one. Way to go oldfart.
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Old 08-29-2010, 11:12 AM
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Default Re: Blend door, heater core, or what????

What do you mean?
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Old 08-29-2010, 11:18 AM
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Default Re: Blend door, heater core, or what????

The spring on the rad cap controls the amount of coolant going to the tank, if the spring is weak it will lift sooner and let coolant go to the tank before the radiator is up to pressure.
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