How to Replace a Heater Core on a 98 Civic

It's winter, and the heater on your Honda Civic just went out. A bad heater core might leak antifreeze into the passenger compartment or simply not blow hot air. To avoid an expensive repair bill, you can replace the heater core yourself. Removing the heater core requires removing most of the dash of your vehicle, but equipped with the right tools, you can install a new heater core.

Instructions

Accessing the Heater Core

1

If your vehicle is equipped with air-conditioning, have a certified automotive coolant technician evacuate the coolant from the system.

2

Disconnect the battery cable. Disconnect the cable from the dash to the heater valve, and open the valve.

3

Place a basin or other catch pan under the radiator, and drain all the coolant. Disconnect the hoses from the heater core near the bulkhead of the car.

4

Remove any heating unit mounting bolts exposed in the engine bay (look for bolts near the radiator hoses where they pass through bulkhead).

5

Remove the dashboard on the right side and the heating ducts. Disconnect any air-conditioning lines, and remove the heating/air-conditioning unit.

Replacing the Heater Core

6

Remove all of the fasteners holding the heater core in place in the heating unit.

7

Reinstall the heater unit in the dash. Reconnect any air-conditioning lines, the ducts, and reinstall the dash.

8

Tighten any heating unit mounting bolts exposed in the engine bay. Attach the coolant lines that run to the heater core, and clamp them in place.

9

Attach the heater valve cable. Fill the radiator with an appropriate coolant mixture, and attach the battery cable. Run the car with heater on high for several minutes to allow coolant to circulate through all the lines.

10

Have the air-conditioning recharged by a certified technician.