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How to Fix a No Heat Problem on a Jeep Grand Cherokee

by Teri Stryker

Your Jeep heater is blowing cold air and you're not sure why. Two possibilities exist. One is a stuck thermostat. The other possibility is a bad heater core. Replacing the thermostat is fairly easy. The heater core is another story. If you take the Jeep to a mechanic, expect to spend between four to five hundred dollars to get the heater core replaced. You can, however, decide to fix it yourself. The thermostat takes approximately one hour. For the heater core be prepared to spend at least six hours on this repair job.

Drain and refilling the cooling system.

Disconnect the negative cable from the battery. Apply the parking brake. Place a brick or block of wood behind the rear tires. Let the engine cool down.

Place a clean container under the radiator drain plug. Remove the drain plug with a pair of pliers. Remove the radiator cap. Let the coolant drain.

Inspect the radiator hoses for cracks or breaks. Replace any damaged hoses.

Thermostat replacement

Drain the cooling system. Follow the upper radiator hose to engine to locate the thermostat housing.

Loosen the hose clamp using pliers. Pull the hose off of the thermostat housing.

Remove the bolts on the thermostat housing with a socket and ratchet. Remove the housing from the engine.

Remove the thermostat. Put a clean rag in the opening to keep debris out of the engine. Remove the old gasket from both surfaces with a gasket scraper or putty knife.

Remove the rag. Install the new thermostat with the spring facing outward. Apply a layer of RTV sealant to both sides of the new gasket. Place the gasket on the thermostat housing.

Install the thermostat housing and bolts. Tighten the bolts with a socket and ratchet. Attach the hose to the housing. Use pliers to position the clamp in the place on the hose.

Close and tighten the radiator drain plug. Fill the radiator with antifreeze. Start the engine. Turn the heater on. Add antifreeze to the lowest mark on the coolant reservoir. Let the engine run until the thermostat opens up. Fill the radiator with antifreeze.

Turn the engine off. Let the engine cool. Add more antifreeze to the radiator to bring the level up to the filler neck.

Replace the radiator cap. Start the engine. Let the engine warm to normal operating temperature. Check for leaks at the drain plugs, hoses and clamps.

Jeep Cherokee heater core removal.

Drain the cooling system. Remove the nuts on the coolant reservoir with a socket and ratchet. Empty the coolant into the container.

Loosen the heater hose clamps with a flat-head screwdriver. Remove the hoses.

Use the flathead screwdriver to pop out the two snap-fit bezels on the switch pod just below the instrument cluster.

Remove the trim screws from the instrument cluster bezel with a Phillips screwdriver. Remove the instrument cluster bezel.

Open the glove box. Remove the screws using Phillips screwdriver. Remove the glove box. Remove the panel screws for the surrounding panel with a Phillips screwdriver.

Reach through the left side of the glove box opening to remove the two screws on the backside of the center instrument cluster. Remove the two upper screws from the front side. Move the bezel out to release the bezel from its tab.

Remove the lower steering column trim screws with an Allen head torx wrench. Remove the upper steering column trim.

Remove the knee blocker screws with a Phillips screwdriver. Remove the knee blocker. Disconnect the steering column wiring. Remove two steering column bolts with a socket and ratchet.

Remove the bolts below the steering column with a socket and ratchet. Remove the metal cross section. Lower the steering column. Lay the column on the driver side seat.

.Pry the shift knob up and off of the shift lever. Use a flathead screwdriver to pry off the gear selection panel. Remove the mounting screws with a Phillips screwdriver.

Open the center glove box compartment. Remove the four screws with a Phillips screwdriver. Remove the two screws from inside the compartment with a Phillips screwdriver. Lift the console up over the shift lever. Remove the console from the vehicle.

Pull back the carpet by the shift lever. Remove the two bolts attached to the floor bracket with a socket and ratchet.

Remove the radio mounting screws with a Phillips screwdriver. Pull the radio out. Disconnect the wiring harness from the radio.

Remove the mounting screws from the A/C control panel. Disconnect the wiring from the controls, cigar lighter and power outlet. Detach the lower floor heating duct. Disconnect the a/c vacuum lines.

Pry the defroster grille up with a flathead screwdriver. Remove the four upper nuts with a deep well socket and ratchet. Remove the two side screws with a Phillips screwdriver.

Disconnect any remaining electrical wires. Remove the wiring harness from the clips along the backside of the dash. Disconnect the air bag electrical connector. Remove the dash from the vehicle.

Disconnect the blower motor electrical connector under the black heater/ac unit on the passenger's side. Disconnect the A/C lines at the firewall using a spring-lock coupling tool.

Remove the computer mounting bolts with an extension, socket and ratchet. Do not disconnect the computer electrical harnesses. Place the computer on the reservoir tray. Remove the heater/A/C nuts with socket and ratchet.

Label the wiring harnesses for the A/C unit and blower motor resistor. Disconnect the electrical connectors. Pull on the vacuum hose at the vacuum motor on the housing unit to disconnect the hose.

Pry the rear floor heat duct loose. Move the duct out of the way. Remove the bolts on the firewall with a socket and ratchet. Remove the heater/a/c unit from the vehicle. Pull the heater core out of the housing unit.

Installing the Jeep Cherokee heater core.

Install the new heater core in the housing.

Position the heater/ a/c unit in the Jeep. Install the bolts with a socket and ratchet. Push the rear floor heat duct onto the bottom heat duct.

Install the vacuum hoses to the vacuum motor. Connect the wiring for the A/C unit and blower motor. Install the nuts on the outside firewall with socket and ratchet. Install the computer mounting bolts using a socket and ratchet. Push the A/C lines to together at the firewall.

Connect the blower motor electrical connector to the blower motor. Place the dash in the Jeep. Connect the wires for the airbag. Run all wiring to the proper positions. Install the screws on the left center console mounting bracket.

Install the metal cross section bolts, under the steering wheel with a socket and ratchet. Install the center bolt above the steering wheel with a socket and ratchet. Lift the steering wheel and install the two bolts with a socket and ratchet.

Connect the three wiring harnesses to the steering electrical connectors. Install the steering trim cover pieces with an Allen head torx wrench.

Install the dash mounting screws on the top left and right sides with a Phillips screwdriver. Install the retaining nuts with a socket and ratchet. Install the defroster grille. Connect the heater/a/c vacuum lines and electrical connectors.

Connect the wiring harness and antenna to the radio. Place the radio in the center panel. Install the screws with a Phillips screwdriver. Install the nuts on the bolts inside the floor mounted bracket with a socket and ratchet, and put the carpet back in place.

Push the knee blocker into place. Install the heater/a/c control switch. Tighten the screws with a Phillips screwdriver. Install the two screws behind the panel by reaching through the left side glove box opening.

Install the glove box bin and screws with a Phillips screwdriver. Install the instrument cluster bezel. Tighten the screws with a Phillips screwdriver. Snap the trim panels into place

Close and tighten the radiator drain plug. Fill the radiator with antifreeze. Start the engine. Turn the heater on. Add antifreeze to the lowest mark on the coolant reservoir. Let the engine run until the thermostat opens up. Fill the radiator with antifreeze.

Turn the engine off. Let the engine cool. Add more antifreeze to the radiator to bring the level up to the filler neck.

Replace the radiator cap. Start the engine. Let the engine warm to normal operating temperature. Check for leaks at the drain plugs, hoses and clamps.

Release the parking brake. Remove the brick or block of wood from behind the rear tires.

Tip

  • Use a magnetic tray to keep the bolts, nuts and screws from getting lost.

Warnings

  • Take the Jeep to an automotive shop to have the a/c system discharged.
  • After replacing the heater core, have an automotive shop evacuate and recharge the a/c system.

Items you will need

References

About the Author

Based out of Texas, Teri Stryker has been writing since 2009. As an online contributor to eHow, her writing focuses on topics in automotive, cooking and home repair. Stryker is pursuing a Bachelor of Science in criminal justice from the University of Phoenix.

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Photo Credits

  • car heater vent image by robert mobley from Fotolia.com