Heater Core: Service and Repair

1. Disconnect battery ground cable, then remove plenum as follows:
a. Disconnect heater hoses from core. Plug hoses and heater core tubes to prevent coolant loss during core removal.
b. On models equipped with A/C, remove three nuts located below windshield wiper motor retaining left end of plenum to dash panel.
c. On models equipped with A/C, remove one nut retaining upper left corner of evaporator case to dash panel.
d. On all models, remove left and right lower I/P insulators.
e. Disconnect vacuum supply hose from vacuum source, then push grommet and hose into passenger compartment.
f. Remove glove compartment, then loosen right door sill plate and remove right side cowl trim panel.
g. Remove bolt retaining lower right end of I/P to side cowl.
h. Remove screws retaining I/P pad at each defroster opening.
i. Remove screw retaining each outboard end of pad to I/P.
j. On LTD Crown Victoria models, remove one pad attaching screw from upper right corner of glove compartment door.
k. On all models, remove five screws retaining lower edge of I/P pad, then pull I/P pad rearward and remove from vehicle.
l. On models equipped with Automatic Temperature Control System, disconnect temperature control cable and vacuum harness connector from ATC sensor, then disconnect ATC sensor tube from sensor and evaporator case connector.
m. On models less A/C, remove one bolt located below windshield wiper motor retaining left end of plenum to dash panel.
and. On models less Automatic Temperature Control System, disconnect temperature control cable housing from bracket at top of plenum, then disconnect cable from temperature blend door crank arm.
o. On all models, disconnect vacuum jumper harness from multiple vacuum connector near floor air distribution duct, then disconnect white vacuum hose from outside-recirculating door vacuum motor.
p. Remove screws retaining passenger side of floor air distribution duct to plenum. It may be necessary to remove the two screws retaining partial (lower) panel door vacuum motor to mounting bracket to gain access to right screw.
q. Remove plastic push fastener retaining floor air distribution duct to left end of plenum, and remove floor air distribution duct.
r. Remove nuts from the two studs along lower edge of plenum.
s. Carefully move plenum rearward to allow heater core tubes and stud at top of plenum to clear holes in dash panel. Remove plenum by rotating top of plenum forward, down and out from under I/P. Carefully pull lower edge of I/P rearward as necessary while rolling plenum from behind instrument panel.
2. On models equipped with Automatic Temperature Control System, remove ATC servo from plenum.

Fig. 5 Typical heater core removal. 1982---88:

3. On all models, remove the four retaining screws from heater core cover and remove cover from plenum, Fig. 27.
4. Remove heater core retaining screw, then pull core and seal assembly from plenum assembly.
5. Reverse procedure to install.