BLOWER MOTOR CIRCUIT
Mode (Function Selector) Switch
When the heater mode switch is in any position except OFF, power is supplied to the coil circuit of the blower motor relay. When the heater mode switch is in the OFF position, the blower motor will not operate.
Blower Motor Relay
Blower motor relay is located under left side of dash, in fuse/relay block. When current flows from the heater mode switch to the blower motor relay, it passes through the coil circuit to ground. This causes the contacts in the relay to close, allowing power to the blower motor.
Blower Motor Switch
The blower motor switch completes the blower motor ground circuit by directing current through one or more of the blower motor resistors (except high speed), or directly to ground through the blower motor switch (high speed).
Blower Motor Resistor
Blower motor resistor is located behind glove box, near blower motor. The blower motor is grounded through all 3 resistors (low speed), 2 resistors (medium-low speed), or one resistor (medium-high speed).
The thermal limiter is part of the blower motor resistor. If airflow through the system is reduced or stopped (due to a locked blower motor wheel, etc.), The blower motor resistor may overheat, damaging the heater housing. If the temperature of the blower motor resistor increases to about 250 F (121 C), the thermal limiter opens the blower motor circuit. The thermal limiter cannot be serviced separate from the blower motor resistor.
HEATER CONTROL PANEL
Removal & Installation
Disconnect negative battery cable. Install Radio Removers (T87P-19061-A) into radio face plate. Push radio removers about 1" (25.4 mm) into face plate to release retainer clips. Slightly spread removers, then remove radio. Remove radio chassis.
Remove 4 screws attaching finish panel. Disconnect headlight dimmer switch connector. Remove finish panel by pulling it away from dash. Remove 2 screws and A/C-heater control panel. Disconnect electrical and vacuum harness connectors. To install, reverse removal procedure.