Yes it's the heater core, It's a complicated diy job and unless you are an experienced mechanic you are going to need a good workshop manual for the job.
did you check rad 4 leaks and make sure all aluminum mesh is intaced beetween cores i had a jeep do same thing or could possibly have air pocket let run with cap off while circulating through block check fluid level add if nessisary also they sell a very good product called water wetter its a synthetic helps fluid flow freer good luck
No, you don't have to pull the whole dash board but you have to pull a few panels....here is the steps on how to get to it and remove and replace it:
Disconnect the negative battery cable.
Drain the cooling system and disconnect the heater hoses from the heater core tubes. Plug the hoses and the heater core tubes to prevent coolant leakage.
CAUTION
NEVER open, service or drain the radiator or cooling system when hot; serious burns can occur from the steam and hot coolant. Also, when draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantities. Always drain coolant into a sealable container. Coolant should be reused unless it is contaminated or is several years old.
Remove the 3 nuts located below the windshield wiper motor attaching the left end of the plenum to the dash panel. Remove the 1 nut retaining the upper left corner of the evaporator case to the dash panel.
Plenum removal—1990-98 vehicles
Disconnect the vacuum supply hose(s) from the vacuum source. Push the grommet and vacuum supply hose(s) into the passenger compartment.
Remove the right and left lower instrument panel insulators.
On 1989 vehicles:
Remove the 3 glove compartment hinge screws, disconnect the check arms and remove the glove compartment.
Loosen the right door sill plate and remove the right side cowl trim panel.
Remove the bolt attaching the lower right end of the instrument panel to the side cowl.
Remove the instrument panel pad as follows:
Remove the 2 screws attaching the pad to the instrument panel at each defroster opening. Be careful not to drop the screws into the defroster openings.
Remove the one screw attaching each outboard end of the pad to the instrument panel.
On Crown Victoria, remove one pad attaching screw near the upper right corner of the glove compartment door.
Remove the 5 screws attaching the lower edge of the pad to the instrument panel. Pull the instrument panel pad rearward and remove it from the vehicle.
On 1990-98 vehicles:
Remove all instrument panel mounting screws and pull the instrument panel back as far as it will go without disconnecting any wiring harnesses.
Make sure the nuts attaching the instrument panel braces to the dash panel are removed.
Loosen the right door sill plate and remove the right side cowl trim panel.
If equipped with manual air conditioning, disengage the temperature control cable housing from the bracket on top of the plenum. Disconnect the cable from the temperature blend door crank arm.
If equipped with Automatic Temperature Control (ATC), proceed as follows:
On 1989 vehicles, disconnect the temperature control cable from the ATC sensor.
Detach the vacuum harness line connector from the ATC sensor harness and detach the electrical connector from the ATC servo connector.
On 1990-98 vehicles, remove the cross body brace and disconnect the wiring harness from the temperature blend door actuator. Detach the ATC sensor tube from the evaporator case connector.
Detach the vacuum jumper harness at the multiple vacuum connector near the floor air distribution duct.
Disconnect the white vacuum hose from the outside-recirculating door vacuum motor.
Floor air distribution duct removal—1990-98 vehicles
Remove the 2 hush panels.
Remove 1 plastic push fastener retaining the floor air distribution duct to the left end of the plenum.
Remove the left screw and loosen the right screw on the rear face of the plenum and remove the floor air distribution duct.
Remove the 2 nuts from the 2 studs along the lower flange of the plenum.
Heater core removal—1990-98 vehicles
Carefully move the plenum rearward to allow the heater core tubes and the stud at the top of the plenum to clear the holes in the dash panel. Remove the plenum from the vehicle by rotating the top of the plenum forward, down and out from under the instrument panel. Carefully pull the lower edge of the instrument panel rearward, as necessary, while rolling the plenum from behind the instrument panel.
On 1989 vehicles with ATC, remove the ATC servo from the plenum.
Remove the 4 retaining screws from the heater core cover and remove the cover from the plenum assembly.
Pull the heater core and seal assembly from the plenum assembly.
To install:
Carefully install the heater core and seal assembly into the plenum assembly. Visually check to ensure that the core seal is properly positioned. Position the heater core cover and install the 4 retaining screws.
On 1989 vehicles with ATC, install the ATC servo on the plenum.
Route the vacuum supply hose through the dash panel and seat the grommet in the opening.
Position the plenum under the instrument panel with the register duct opening up and the heater core tubes down. Rotate the plenum up behind the instrument panel and position the plenum to the dash panel. Insert the heater core tubes and mounting studs through their respective holes in the dash panel and the evaporator case.
Install the 3 nuts on the studs along the lower flange and one on the upper flange of the plenum. Install the 3 nuts below the windshield wiper motor to attach the left end of the plenum to the dash panel and the one nut to retain the upper left corner of the evaporator case to the dash panel.
Position the floor air distribution duct on the plenum. Install the 2 screws and plastic push fastener. If removed, position the panel door vacuum motor to the mounting bracket and install the 2 attaching screws.
Connect the white vacuum hose to the outside-recirculating door vacuum motor. Attach the vacuum jumper harness to the plenum harness at the multiple vacuum connector near the floor air distribution duct. Install the floor duct.
If equipped with manual air conditioning, connect the temperature control cable housing to the bracket on top of the plenum and connect the temperature control cable to the temperature blend door crank arm. Adjust the temperature cable.
If equipped with ATC, proceed as follows:
On 1989 vehicles, connect the temperature control cable to the ATC sensor and adjust the cable. Route and attach the vacuum harness connector to the ATC sensor and attach the electrical connector to the ATC servo connector. Do not block the sensor aspirator exhaust port with the excess vacuum harness. Install the ATC sensor tube between the sensor and the evaporator connector.
On 1990-98 vehicles, attach the ATC sensor tube to the evaporator case connector. Install the cross body brace and connect the wiring harness to the blend door actuator.
Install the bolt to attach the lower right end of the instrument panel to the side cowl. Install the right side cowl trim panel and tighten the right door sill plate attaching screws.
On 1989 vehicles, install the instrument panel pad and the glove compartment door. On 1990-98 vehicles, push the instrument panel back into position and install all instrument panel mounting screws. Install the right and left lower instrument panel insulators.
Connect the vacuum supply hose(s) to the vacuum source.
Install the right and left lower instrument panel insulators and install the 2 hush panels.
Unplug the heater core tubes and the heater hoses and connect the heater hoses to the heater core tubes. Fill the cooling system.
Connect the negative battery cable and check the system for proper operation.
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Evaporator core is located behind the dash board, passenger side, inside heater box along with heater core and blower motor. It is basically a mini radiator that carries your Freon from your a.c. and your blower blows air across it, which is where your cold air conditioning comes through. Hope that helps explain a little.
not sure on your cherokee but often there is a valve in the heater hose line just as the water enter the heater core .. the valve is controled by the the selection of heat or cool .. those valves frequently clog up and need replaced ... you might also have an air lock in your heater core .. if air is trapped in there then it doesnt want to come out and it occupies a portion of the heating surface .. you can take the top heater hose loose with the engine running but not hot .. that will blead off any air in the core .. it will also show you if you have a clog .. you should have lot of water flow thru there with the engine running .. you may also have a bad thermostat .. if that the case then the engine wont get up to temperature preventing the heater from working properly ..
When I turn my heater on, after my 1993 Jeep Grand Cherokee has warmed up, there is a dusty, watery smell for a few minutes, then it goes away. Also, it doesn't put out as much heat as I think it should. I don't think the heater core has a leak, because I always seem to have the same amount of coolant in the radiator and the heater core is not leaking on the inside of the truck.
I have a 1993 Jeep Wrangler YJ...My heater core needed replacement when I bought it about a year ago. I made the mistake of taking apart the dash to get to the heater core. DO NOT DO THIS!!! It is actually 4 screws that you must take out from the inside of the engine compartment on the firewall. Then it will come right out. Have fun!!!
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