How to Replace a 1979 Ford F150 Blower Fan Motor

There was a time when automakers routinely made heater core, evaporator and blower motor replacements seemingly as difficult as possible. On older vehicles, the blower motor was often hidden behind the heater core, with no access for replacement without tearing half the dash apart. On newer vehicles, though, the blower motor is often quite easy to get to; you simply remove a few screws and pop that baby out. But, unfortunately, your '79 F150 isn't new -- so get comfortable.

Instructions

Removal

1

Disconnect the negative battery cable to prevent electrical shocks while splashing around. Place a clean drain pan under your lower radiator hose, remove the radiator hose clamp and drain about three gallons of coolant out of your system. You only need to drain enough so that the heater core isn't full of water. When you're done, you can remove the carburetor air cleaner, and then remove the two hoses from the heater core at the firewall.

2

Remove the screw securing the A/C hose support bracket to the cowl. Remove the insulation tape from your A/C system's expansion valve and sensing bulb. Then remove the two screws securing the cover plate and seal from the evaporator housing at the expansion valve, and remove the cover plate.

3

Go inside the truck. Remove the inner glove box liner, and pull the A/C duct from the instrument panel register after releasing the clip at the A/C duct central chamber. Remove the right cowl fresh-air inlet vacuum hose that connects to the air door vacuum motor. Remove the evaporator rear housing from under the instrument panel. Then remove the four nuts and one bolts that secures the air inlet to the evaporator housing. Pull the housing out, and reinstall one upper nut to hold the housing back in place upon re-installation.

4

Disconnect the de-icing switch wires, pull the tube out of the evaporator core, and remove the four screws that secure the de-icing switch mounting plate. Unscrew the two screws securing the plenum to the dash above the transmission tunnel, and then the two screws that secure the evaporator case, and remove the plenum (central air chamber).

5

Remove the lower-right instrument-panel-to-A-pillar bolt and hold the panel rearward. Remove the four evaporator retaining screws, and pull the evaporator back and up to get it out of the way. Remove the evaporator sealing grommet. Remove the three screws and two plates that secure the heater core, and then remove the heater core. Take the A/C-Heater door ff, and remove the two arm support screws and one pivot screw to free the door. Finally, remove the two screws that secure the blower motor, and remove it. Unplug the motor from its harness.

Installation

6

Reinstall the new blower and fan assembly. Install the door arm pivot retainer and its two screws. Snap the heater door back into place. Reinstall the heater core, being very careful not to damage its fins. Remove the retainer that holds the evaporator away from the case, and reinstall the evaporator and evap grommet.

7

Install the plenum and tighten the four screws that secure it, then install the de-icing switch mounting plate and evaporator capillary tube. Connect the blower motor and de-icing switch harnesses. Remove the nut that you reinstalled to hold the upper evaporator case in place, and reinstall then move the air inlet bellows into position.

8

Connect the cowl inlet vacuum hose to the fresh-air-door's vacuum motor. Put the instrument panel back into place, and install the panel and A-pillar's retaining bolts. Back under the hood, install the seal and cover plate over the expansion valve and sensing bulb, then reinstall the insulation. Screw the A/C hose support back to the firewall, and reconnect the heater core hoses to the core.

9

Install the air cleaner, and refill the coolant with either fresh coolant, or the coolant you recovered with your clean drain pan. Reconnect the battery, and check blower motor operation.