How to Replace Civic Heater Core

by Pheori Wiley

The Honda Civic is one of the most popular cars on the road today--the car has a reputation for being of good quality, packed with features and built to last a long time with little or no major maintenance or repairs required. If, however, you need to replace your older Civic's heater core, you should be familiar with the construction of the car's interior before attempting the procedure.

Step 1

Disconnect the battery cable from the negative side. Wait a full 5 minutes for the car's PRS Air Bag System to discharge. (The manufacturer's recommendation is to wait 3 minutes; waiting 5 minutes will ensure the system is completely discharged.)

Step 2

Disconnect the air conditioner system by disconnecting the suction line and the receiver line from the compressor; unscrew the retainer nuts that hold them in place using a pair of pliers.

Step 3

Drain the coolant from the radiator by opening the drain plug on the bottom of the radiator. Use an approved drain pan to collect the coolant and dispose of it in a method compliant with the laws of your community. Remember this substance is poisonous.

Step 4

Open the cable clamp located under the hood and disconnect the heater control cable. Turn the control valve of the core to the fully open position by hand.

Step 5

Disconnect the heater hoses from the core housing; squeeze open the hose clamps using a pair of vise grips and remove the mounting wing nut from the heater unit by turning it with your hand until it comes free.

Step 6

Remove the center console from the interior of the vehicle using the screwdriver. Remove the gear shift knob and disconnect the heat switch connectors (which should just pull out of the switches); front power accessory port and rear power accessory port (which should just pull out of the socket connectors); and illumination power cables (which should simply un-clamp by hand with squeeze connectors).

Step 7

Remove the lower dashboard panels, driver glove box and center storage pocket using the screwdriver.

Step 8

Carefully remove the airbag assembly from the steering wheel and the passenger side. The airbags are held in place with spring clamps, which will pop open with mild pressure. Be careful to not apply too much pressure--even a discharged airbag may still deploy if too much shock is applied.

Step 9

Separate the steering column assembly from the dashboard unit by moving the column to the fully up position. Use a piece of heavy tape to secure the shaft sliding cover onto the steering column while it is removed.

Step 10

Remove the hoses by opening the spring hose clamps using the vise grips. Remove all remaining wires. Remove the harnesses and retainer bolts using the Phillips screwdriver. Remove the connectors, air bag control computer and center lower covers by squeezing open the hand squeeze clamps. (This may require the assistance of another person.)

Step 11

Lift the dashboard out slowly and remove it from the vehicle by sliding it out of one of the doors.

Step 12

Unplug the connectors from the air mix control motor unit, temp sensor, recirculation control motor, heater ducts, power transistor and blower fan unit.

Step 13

Loosen the heater core cover with the screwdriver and pull the heater core out of the housing unit.

Step 14

Install the new heater core by inserting it into the housing, then securing it in place with the housing cover using the screwdriver.

Step 15

Reconnect and reinstall everything you removed in reverse order.

Step 16

Close the drain valve on the radiator and refill it with fresh coolant. HINT: This would be a great time to perform cooling system maintenance; pick up a flush and fill kit and clean out the engine's cooling system before refilling. You also might want to use a cooling system treatment when you refill, especially if you have an older car.

Step 17

Test the heating system with normal operation and inspect the whole system for leaks.

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