2. Locate the heater blower motor relay. On Mazda models, this turnip is located in the front right corner of the engine compartment. There are two relays on Ford Probe models: on 1993 models, the low fan speed relay is located on the right in front of the radiator, and on later models, in the left rear corner of the engine compartment, between the upper suspension support and the engine bulkhead. The high fan speed relay is located in the fan assembly on the right under the dash (see fig. 10.4). Remove the relays and check their operation (see chapter 12). If the relay is defective, replace it.
3. Set the transmission selector to the Park position, apply the parking brake and turn on the ignition. It is not necessary to start the engine.
4. The heater fan is located behind the front panel under the glove box near the engine bulkhead (pic. 10.4).
5. Set the airflow switch to FLOOR and turn on the fan at the highest speed. Listen to those air ducts to see if air is moving underneath. If the fan is running, switch it to a lower speed and check again that the fan is running. Check fan operation at other speeds.
6. If the fan does not work and the fuses and relays are good, check the fan motor (see fig. 10.4). Without disconnecting the motor connector, insert the tester probe to the output of the blue and red wires (Mazda) and whether the white wire (Probe). With the ignition on, the tester should show at least 10 volts in any speed switch position other than OFF. If it doesn't, then there is a faulty circuit somewhere between the fuse and the motor, including the motor relay (Mazda) or low speed relay (Ford).
7. If there is voltage at the input to the motor, and the fan does not work, connect the jumper from the blue wire to the white wire (Mazda), or black with orange wire (Ford) with mass. If in this case the fan does not work, then the motor is faulty. Replace motor If the motor now runs, then the target from the motor through the resistor and speed switch to ground is faulty.
8. If the motor motor runs but not at all speeds, check the motor resistor. It is located on the fan assembly (see fig. 10.4). The resistor is tapped to provide different fan speeds.
9. Remove the resistor from the car and inspect it for breaks and melted leads and contacts. Check the integrity of the resistor with an ohmmeter (pic. 10.9). If the resistance of the sections of the resistor differs from that indicated in the table, replace the resistor.
10. If the fan runs, but not at all speeds, and the resistor is faulty, remove the heater/air conditioner control panel. On Probe models, disconnect the speed selector connector at the back of the panel and test the switch with a switch tester for an open or loose (pic. 10.10, a). On Mazaa models, do not disconnect the connector, but get behind the probes of the tester or control light to the connector contacts indicated in the table (pic. 10.10, b).
