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Thread: 00 wj heater blowing luke warm

  1. #1
    Master Tech williambmac's Avatar
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    Default 00 wj heater blowing luke warm

    Anyone ever have an issue with the aftermarket heater cores not blowing hot, possibly not enough flow thru them?
    A few months ago i replaced the evap in my wifes wj, while it was apart I also replaced the heater core just for preventative maintainence. Ever since then the heat only blows luke warm, with the exception of being on recirc mode, which it blows a little warmer.
    I know the recirc and blend door motors are functioning.
    The system does not have any air in it.
    Thermostat is opening @ 195 as it should.
    Both heater hoses get piping hot, but still luke warm air?
    I even back flushed the cooling system and heater core, but no luck.
    Any ideas?
    I know there are a ton of threads regarding wj heating problems, but didnt find anything relating to aftermarket heater cores.
    2005 Rubi LJ 35's 5.5 Clayton
    lots of extras

    2000 wrangler 35" Goodyears Rock-trac super 88 hp30 4.88Terminator trans 5.5" RE/Clayton lots of xtras. RIP
    2000 WJ 4.0 addco upcountry springs bilsteins
    2001 H-D Duece Black and Chrome (For Sale)
    1997 YZF1000 200mph Superbike (RIP)

  2. #2
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    Williambmac,

    It should not be your aftermarket heater core - as long as hot coolant goes through it, it will get plenty hot. I replaced my heater core this fall with an AutoZone unit and it gets piping HOT...

    Have you ever replaced any of the sub-assembly doors? I read a statement somewhere that said every WJ ever made would eventually experience sub-assembly door failure.... Every one of them!!!

    Regards,

    Carlos

  3. #3
    Doomsday Prepper Super's Avatar
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    If your WJ is a Limited, it sure sounds like blend doors. mine did the same thing before turning to no heat. Jeep dealership hooked me up for about $65 for a new blend door kit. The doors are made stronger than original, [one is even aluminum]and has instructions on replacing without removing dash. My heater core just started leaking, so my dash is out right now. Replacing just about everything with upgraded parts, since I don't want to do it twice on the same vehicle. If you do a search, there are many threads telling you how to check for codes on the AZC to verify.
    99 WJ Limited 4.6 stroker,QD/D44A my DD
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    84 Land Cruiser FJ60-under the knife getting a 5.9 Cummins,Dana 60, corp 14 bolt, NV5600(my Zombie Apocalypse vehicle)
    85 GL1200A Goldwing(my road sofa)

  4. #4
    Master Tech williambmac's Avatar
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    It's a Laredo with the manual control system.
    I know its not definitely not the blend door as I dropped the blower motor out and peaked around inside with my
    Snap-on borescope. I can see the blend door open/close when I move the temp dial on the control head.
    I back flushed the heater core and hooked it up to a coolant flush machine in the shop.
    The heater hoses get nice and hot, but it will only blow luke warm out the vents.
    This has only been happening since I changed the heater core itself.
    I have checked everything and still have yet to come up with a solution. I really don't want to remove the dash because I know that everything went together the same way it came apart.
    2005 Rubi LJ 35's 5.5 Clayton
    lots of extras

    2000 wrangler 35" Goodyears Rock-trac super 88 hp30 4.88Terminator trans 5.5" RE/Clayton lots of xtras. RIP
    2000 WJ 4.0 addco upcountry springs bilsteins
    2001 H-D Duece Black and Chrome (For Sale)
    1997 YZF1000 200mph Superbike (RIP)

  5. #5
    Registered 01jgcl40's Avatar
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    When mine did the same thing I replaced the thermostat. It appaently was hanging open so the coolant never got warm unless you went a ways. I have a 2001 Laredo.
    3" lift with O.M.E HD springs, KOR .75 spacers, MX6 shocks, K.O.R. SS, Rusty's Adj front and rear LCAs , JKS Adj front UCA's, JKS ADJ Track Bar, Addco front and rear swaybars, Tera A Frame Spacer, K&N intake, relocated MAT sensor and 62mm bored throttle body. Mopar tow hooks front and rear, factory front and transaxle skids.

  6. #6
    Master Tech williambmac's Avatar
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    Quote Originally Posted by 01jgcl40 View Post
    When mine did the same thing I replaced the thermostat. It appaently was hanging open so the coolant never got warm unless you went a ways. I have a 2001 Laredo.

    It has a brand new mopar t-stat that opens at 195 degrees.
    2005 Rubi LJ 35's 5.5 Clayton
    lots of extras

    2000 wrangler 35" Goodyears Rock-trac super 88 hp30 4.88Terminator trans 5.5" RE/Clayton lots of xtras. RIP
    2000 WJ 4.0 addco upcountry springs bilsteins
    2001 H-D Duece Black and Chrome (For Sale)
    1997 YZF1000 200mph Superbike (RIP)

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    does it get hotter when you rev the engine?

  8. #8
    Master Tech williambmac's Avatar
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    Quote Originally Posted by Mike-WJ View Post
    does it get hotter when you rev the engine?

    Nope.
    2005 Rubi LJ 35's 5.5 Clayton
    lots of extras

    2000 wrangler 35" Goodyears Rock-trac super 88 hp30 4.88Terminator trans 5.5" RE/Clayton lots of xtras. RIP
    2000 WJ 4.0 addco upcountry springs bilsteins
    2001 H-D Duece Black and Chrome (For Sale)
    1997 YZF1000 200mph Superbike (RIP)

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