Question about 1999 Jeep Grand Cherokee

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How do i replace/install a heater core for a 1999 limited edition jeep cherokee 4.0 liter 6cyclinder

Need to replace heater core. 1999 limited edition jeep cherokee doesnt blow out any warm air at all. will blow out cold air constantly. its automatic 6cyclinder 4.0 liter

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  • Jeep Master
  • 21,873 Answers

I would make sure the core is the problem. You may have a heater control valve that cuts off flow to the core by vac. or a blend door that cuts off air flow thru the core.
You will need a shop manual to replace the core. The dash and console have to come out, along with discharging the ac.

Posted on Dec 18, 2012


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Posted on Jan 02, 2017



  • 105 Answers

SOURCE: need to replace heating core

  1. Disconnect and remove the negative battery.
    CAUTION After disconnecting the negative battery cable, wait 2 minutes for the driver-s/passenger-s air bag system capacitor to discharge before attempting to do any work around the steering column or instrument.
  2. Drain the cooling system into a clean container for reuse.
  3. Remove the instrument panel by performing the following procedure:
    1. Turn the steering wheel in the straight-ahead position.
    2. Remove the knee blocker from the instrument panel.
    3. Remove the steering column; do not remove the air bag module, the steering wheel or switches from the steering column.
    4. From under the driver-s side of the instrument panel, disconnect the following items:

      Instrument panel wiring harness connector from the 100-way wiring harness connector at the left side of the inner panel. Side window demister hose at the heater/air conditioning housing demister/defroster duct on the driver-s side.
    5. Remove the glove box.
    6. Reaching through the glove box opening, disconnect the following items:

      Two halves of the heater/air conditioning system vacuum harness connector. Instrument panel wiring harness connector from the heater/air conditioning system wiring harness connector. Instrument panel wiring harness connector from the passenger-s side air bag module wiring harness connector. Side window demister hose at the heater/air conditioning housing demister/defroster duct (passenger-s side). Two halves of the radio antenna coaxial cable connector. Two instrument panel wiring harness connectors from the passenger air bag ON/OFF switch wiring harness connector. Passenger-s side air bag ON/OFF switch wiring harness from the retainer clip on the plenum bracket that supports the heater/air conditioning housing just inboard of the fuse block module. Two lower passenger-s side air bag module bracket-to-dash panel nuts.
    7. Remove the upper cover from the instrument panel.
    8. Remove the 3 instrument panel-to-door hinge pillar screws.
    9. Remove the 4 upper instrument panel-to-dash nuts.
    10. Using an assistant, remove the instrument panel from the vehicle.

  4. If equipped with air conditioning, discharge and recover the air conditioning system refrigerant.
  5. Disconnect the refrigerant lines from the evaporator. Plug the refrigerant openings to prevent evaporation.
  6. Disconnect the heater hoses from the heater core tubes.
  7. Disconnect the heater/air conditioning system vacuum supply line connector from the T-fitting near the heater core tubes.
  8. In the engine compartment, remove the 5 heater/air conditioning housing-to-chassis nuts. If necessary, loosen the battery hold-downs and reposition the battery for access.
  9. Remove the cowl plenum drain tube from the heater/air conditioning housing stud; it-s located behind the cylinder head on the cowl.
  10. From the bottom of the heater/air conditioning housing, remove the floor duct.
  11. On the passenger side, remove the heater/air conditioning housing-to-plenum bracket screw.
  12. Pull the heater/air conditioning housing down far enough to clear the defrost/demist and fresh air ducts, then, rearward far enough to clear the mounting studs and the evaporator drain tube to clear the dash panel holes.
  13. Remove the heater/air conditioning housing assembly from the vehicle.
  14. Remove the heater/air conditioning housing upper case.
  15. Lift the heater core from the lower half of the heater/air conditioning housing.a35714c.gif


Posted on Feb 13, 2010


  • 1 Answer

SOURCE: Heater blows cold air when idle

Sounds like you may have a partially plugged heater core. You could flush this out separately, from flushing radiator & engine block. Diconnect heater hoses going to your heater core and clamp off, so not to loose coolant from engine. Now hook up separate hose to one side of heater core pipe and flush out with typical garden hose. Repeat procedure on both heater core inlets. Reconnect original heater hoses and test difference. You may have to add an additional litre of antifreeze. If this don't work i suggest changing heater core. Good luck.........Ron.

Posted on Jan 03, 2009


Brainyass Rabbit

  • 242 Answers

SOURCE: heater only blows warm air.

The hoses from your heater core should be very hot to the touch. Check the hoses going to the core from the water pump. It should be very hot. The return hose should also be very hot. Now check the hoses going to the core. If they are not the same temp, then your heater control valve is not working correctly or the vacuum is not working. At any rate, locate the vacuum line going to the heater valve. Remove the silver bar on the valve from the plastic plunger arm. You will have heat all the time now if it was only a vacuum problem. You can fix it later when it's warmer out. BTW a 200* thermostat will make your heater even hotter.

Posted on Nov 21, 2008


  • 90 Answers

SOURCE: 1999 Jeep Cherokee sport/air vents do not blow out cold or hot while it is on

this sounds like the recirculation door in the heater box is broken and this is a difficult and can be an expensive repair as the dash has to be removed for access. a quick check for this is if you release the glove box and let it hang you will see the heater box if you reach up to the left top you will feel a grid and the recirc flap is housed there you can operate the blower and hot and cold and see if flap moves

Posted on Jun 22, 2009


  • 37 Answers

SOURCE: i need a heater core diagram for jeep grand

auto zone .com

Posted on Nov 02, 2009

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1 Answer

I have a 1999 jeep grand Cherokee limited edition my heater only throws out cold air why is that?

this is easy. (are you moving or parked) ill assume stopped.
first is the blower working, (seems so)
ill guess that no heat in all vent modes, and re-circ, on.
next is the engine fully hot, hot means at 180F or more holding
(we measure it with a pyro gun)
next, are both heater core hoses hot/ at the fire wall? and equal at 180f?
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I suggest review the ZJSecc24-Heating-and-Air-Conditioning

First you'll need remove the heater A/C unit from the vehicle; after, remove the heater core retaining screws, and finally, pull the heatrer core straight out of the housing.

Hop helped with this (remember rated this help) Good luck.

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