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Thread: 1998 jeep cherokee heat

  1. #1

    Default 1998 jeep cherokee heat

    Sometimes the heat in my 1998 Cherokee works, sometimes not. Lately not so much. Someone mentioned that it might be my thermostat. Any truth to this? If so, is this an easy fix? Besides not getting any heat in my cherokee, is there anyway to perform some type of diagnostic to tell if the heater core has failed? I'm told that this is a pricey repair at the dealer and not to try doing this on my own. Can someone help? Thanks.

  2. #2
    Registered redeye202's Avatar
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    Quote Originally Posted by mtrstoner View Post
    Sometimes the heat in my 1998 Cherokee works, sometimes not. Lately not so much. Someone mentioned that it might be my thermostat. Any truth to this? If so, is this an easy fix? Besides not getting any heat in my cherokee, is there anyway to perform some type of diagnostic to tell if the heater core has failed? I'm told that this is a pricey repair at the dealer and not to try doing this on my own. Can someone help? Thanks.
    Warm up the jeep to operating temp then grab the 2 hoses that go to the heater core,they both should be hot.
    redeye202

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    Quote Originally Posted by mtrstoner View Post
    Sometimes the heat in my 1998 Cherokee works, sometimes not. Lately not so much. Someone mentioned that it might be my thermostat. Any truth to this? If so, is this an easy fix? Besides not getting any heat in my cherokee, is there anyway to perform some type of diagnostic to tell if the heater core has failed? I'm told that this is a pricey repair at the dealer and not to try doing this on my own. Can someone help? Thanks.
    it would only be the thermostat if the engine is not reaching operating temperature.

    if the heater core failed it would be leaking. you need to check if its plugged up as redeye said.

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    Yeah, the cooling system may need to be flushed. Your heater core is okay if you're not smelling coolant in the cabin area.

  5. #5

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    First question that needs to be answered is what temperature is your engine running at? After warmup, should be consistently in the 200-210 range. Start there...
    99 XJ Sport, 4.0, A.T. NP242 "Daily Driver"
    Past Jeeps: 49 Willys, 81 Scrambler, 88 Cherokee

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    Registered Jimmythejett's Avatar
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    do you have enough anti-freeze in your radiator is it full? if you don't have enough and your heater core runs dry you won't get any heat either...
    2001 XJ "Amber Fire Clearcoat"
    2" Lift, JKS Quicker Disco's, Rubicon Rims with BFG A/T's, K&N Filter, Optima Red Top, Kickers, Python Security/Remote Start...

  7. #7

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    I would look at all of the above first. I had the same problem with my 98. The coolant level was full and I installed a new thermostat. The engine would get to normal operating temp but I had very little heat, even after flushing the cooling system with chemicals and pulling the heater hoses and running a hose through the heater core. You would not imagine all of the black muck that came out when doing the initial flush, I thought I was going to have coolant leaks in the radiator or heater core for sure, but I lucked out. I read somewhere on here that a guy drained the cooling system and filled it with water. He then added a cup of powdered dishwasher detergent, drove the vehicle for an hour or so, and then he did another good flush. I did this and got another huge amount of crap out of the cooling system. My heater gets too hot sometimes now. I live in Denver and the temps here have been between -15 to 30 here lately. My heater has been working great every day.

    I wish I knew who suggested the dish washing soap because I need to thank him. The next step for me would have been to replace the heater core. That guy saved me a ton of hassle.

    Scott

  8. #8

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    Scott, thanks for the reply. Is the coolant level the same as the anti-freeze level? Please excuse the ignorance. I'm pretty sure I'm at 200-210 temp. But flushing the coolant system, pulling the heater hoses and running a hose through the heater core. All the stuff you talk about sounds good but I'm a novice w/ this stuff. Not afraid to try but would appreciate some guidence. And it sounds like you got the smarts. Thanks for the help

  9. #9

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    jimmythejet, thanks for the reply, very helpful.

    mtrstoner

  10. #10

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    lakerXJ, thanks for the reply, very helpfull.

    mtrstoner

  11. #11

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    topless xj, thanks for the reply, very helpfull.

    mtrstoner

  12. #12

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    stam89xj, thanks for the reply, very helpfull.

    mtrstoner

  13. #13

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    redeye202, thanks for the reply, very helpfull.

    mtrstoner

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    did you fix the problem?

    you could just take it to a service station and have them flush the heater core and cooling system.

  15. #15

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    stam89xj, just talked to my local jeep dealer and they tell me it's the blend and mode doors that are malfunctioning. This is a $1400 repair!! The whole dash needs to be removed.
    I'm gonna try the cooling and heater core flush first. Only $168. Probably needs to be done anyway. Thanks for the help. mtrstoner

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    Registered wim hoppenbrouwers's Avatar
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    Hallo mtrstoner. You can check the Heater Control Valve in the enginebay. It's were the big coolant hoses meet the small heater hoses.
    It's controlled by a cable or vacuum. :bugeyed:

    Don't spent too much money, you will find the problem yourself.
    '92 XJ 31"BFG muds BB3"

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    Quote Originally Posted by wim hoppenbrouwers View Post
    Hallo mtrstoner. You can check the Heater Control Valve in the enginebay. It's were the big coolant hoses meet the small heater hoses.
    It's controlled by a cable or vacuum. :bugeyed:
    dont think the newer 97 and up models have the vacuum activated heater control valve. there is always coolant running through the heater core.


    mtrstoner,

    i usually dont bad mouth dealerships because ive always got good service and good prices on new parts, but i find it hard to believe that a blend door problem is a $1400 repair, especially if its just a vacuum problem!!

    you need to check all the vacuum lines in the engine bay for cracks or i if they are disconnected. check the vacuum lines that run under the battery tray and to the vacuum reserve ball in the front passenger side of the bumper. battery acid/corrosion will sometimes damage the lines that are under the batt tray. make sure the line(s) are secured to the vacuum reserve ball in the passenger side front bumper and check the reserve ball for cracks.

    then i would check in/under the passenger side of the dash for a broken or disconnected vacuum line. you may have to take the dash trim pieces off to get a better look.

    do you have cruise control? if so, make sure the vcacuum line for the cruise control is connected, i bellieve it is under the dash and connected to the brake pedal arm

    maybe im off based with it being a vacuum issue, but i cant see a blend door issue as a $1400 repair. now on the other hand, i can see a dealership charging that much to replace the heatercore and evap system.

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