How to Replace the Heater Core on a 1989 Crown Victoria

Replacing a heater core and repairing the heating system is rarely an easy task, and doing so for the 1989 Crown Victoria is especially difficult. The Crown Victoria&039;s heater core is stored within a plenum assembly that is mounted behind the instrument panel in the car&039;s interior; you must disassemble the instrument panel and remove the plenum in order to access and remove the heater core.

Instructions

Removal - Exterior

1

Disconnect the car&039;s negative battery cable.

2

Open the coolant tank cap in the engine, then place a large container under the radiator&039;s lower corner. Stick a 3/8-inch diameter hose on the drain fitting in the corner, and loosen the fitting with a wrench to drain the coolant. Repeat for the engine block drain plugs.

3

Squeeze the hose clamps on the heater core tubes ad slide them off, then disconnect the tubes and plug them with rubber.

4

Unscrew and remove the three nuts below the windshield wiper&039;s motor on the firewall with your wrench, followed by the one nut on the evaporator case&039;s upper left corner.

5

Disconnect the vacuum hoses from the car&039;s vacuum source, then push the supply hose and its grommet into the passenger compartment.

Removal - Interior

6

Remove the instrument panel trim moldings, the left and right instrument panel insulators, the steering column covers, the door sill plates and the defroster grille. Use a screwdriver on the screws, and pry off the panels with a trim stick where needed.

7

Disconnect the shift indicator cable from within the steering column, then remove the reinforcement brace from underneath the column. With the front wheels pointing forward, remove the steering column&039;s retaining nuts with a wrench, and lower the column.

8

Open the glove compartment and lower it by depressing the tabs.

9

Remove all the retaining bolts for the instrument panel with your wrench; these will be behind the removed trim panels and within the defroster ducts and glove compartment.

10

Pull the instrument panel back as far as you can without disconnecting the wires behind it.

11

Remove the cross-body brace. Disconnect the temperature blend door actuator&039;s wiring harness, followed by the temperature control sensor tube at the evaporator case connector.

12

Disconnect the jumper harness at the vacuum connector near the floor air duct, followed by the vacuum hose at the outside-recirculating door vacuum motor. Remove the plastic push fastener and the left screw for the air duct, loosen the right screw with the screwdriver and remove the air duct.

13

Unscrew the two nuts along the plenum&039;s lower edge with a wrench, then move the plenum rearward until the heater tubes and the top stud clear the holes in the dash panel.

14

Rotate the plenum&039;s top end forward, down and out of the instrument panel, then pull the panel&039;s lower edge to the rear while you roll the plenum out from behind the panel.

15

Unscrew and remove the heater core cover using a screwdriver, then pull the heater core and its seal out of the plenum assembly.

Installation

16

Install the new heater core with its seal into the plenum assembly, then close and screw the heater core cover in place.

17

Route the vacuum supply hose back through the dash panel, and seat its grommet within the opening.

18

Place the plenum under the instrument panel with its register duct open and its heater tubes pointing downward. Rotate the plenum upward and behind the instrument panel, then position it to the dash panel.

19

Connect the heater core tubes and their mounting studs through their holes in the dash panel and the evaporator case.

20

Re-install the air duct, then connect and tighten all its mounting nuts and screws using your wrench and screwdriver.

21

Reconnect all wiring harnesses, tubes and hoses to the vacuum motor, the air distribution duct and the temperature control system, then reconnect the cross-body brace.

22

Connect the instrument panel in place followed by all the dash trim panels in the reverse order of removal.

23

Reconnect all hoses, nuts and tubes in the engine compartment--this includes the plenum&039;s nuts on the firewall, the vacuum supply hoses to the vacuum source and the heater core tubes.

24

Refill the cooling system with fresh coolant--half water and half antifreeze--at the radiator filler neck.

25

Reconnect the car battery at the negative cable.