How to Replace the Heater Core in a Nissan Altimaby Contributor; Updated November 07, 2017
Items you will need
Replacament heater core
Jack and jack stands
How to Replace the Heater Core in a Nissan Altima. The Nissan Altima's heater core is inside the heater unit near the air conditioning housing assembly. Removing it isn't simple, because you must remove the instrument panel from inside the car in order to get to the heater unit. Be sure you're prepared for this challenging repair before starting.
Make sure the Nissan Altima's front wheels are in the straight-ahead position. With the ignition off, disconnect both battery cables, starting with the negative. Wait at least 10 minutes for the air bag's energy to deplete before continuing.
Detach the driver side air bag and steering wheel. Disconnect the air bag module connector and horn electrical connector from inside the wheel's lids. Use a T150 wrench to remove the bolts Store the air bag module face up.
Take out the passenger side air bag. Remove the glove box to reach the module connector.
Jack up the Nissan Altima and securely place it on jack stands. Place a clean container directly underneath the drain plug located on the bottom of the radiator on the passenger side. Carefully remove the drain plug and drain the engine coolant from the cooling system. Put the drain plug back in place and set the coolant aside.
Discharge air conditioner refrigerant. If your car used R-12 refrigerant, it's against the law for you to discharge or recharge the system unless you're an EPA-certified technician, so you may need a professional to do this part. Disconnect the heater hoses from the heater core tubes from within the engine compartment.
Remove the instrument panel from the car. Remove the lower panels first starting on the driver side. Removal includes all the screws and connectors, the audio/deck pocket, switch panel, center console, grilles, pillar garnish, instrument stay and steering member. You may need assistance taking the panel out.
Disconnect the air conditioning housing by taking off the refrigerant lines and thermo control amp. Remove the heater unit from the car and the heater core from the unit.
Install the replacement heater core to the heater unit. Replace the heater unit and air conditioning housing within the car, reconnecting all the lines.
Reinstall the instrument panel, including the steering member, instrument stay assembly, pillar garnish, grilles, center console, switch panel and audio/deck pocket.
Reconnect the heater hoses to the tubes. Connect the steering wheel, both airbags and the glove box back onto the car.
Fill the cooling system. Use new coolant, if you're not certain the old liquid is still good. Recharge the air conditioning refrigerant (unless it requires an EPA-certified technician). Reconnect both battery cables, starting with the positive one.
Run the Altima's engine to its normal operating temperature. Check the climate control operation and inspect the system for leaks.
Use a clean container to recover the coolant, if you plan on reusing it.