Blower Motor Does Not Operate - Mazda MX-5 1990 Workshop Manual

TROUBLESHOOTING GUIDE
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Symptom; Blower motor does not operate.
Normal operation of blower motor
Blower motor speed is controlled by the blower switch and a resistor assembly in the blower unit.
When the blower switch is in the OFF position, the motor ground circuit is open and the blower motor does
not operate. When the switch is in the first (Low) position, current flow from the blower motor is restricted
by the three resistors in the resistor assembly, and the blower motor turns at low speed.
Changing the blower switch to the second (Mid), third (High), or fourth (Super-high) position causes the cir-
cuit resistance to decrease, and the blower motor speed becomes correspondingly faster.
FUSE BOX
05UOUX-006
Step 1
1. Check the circuit breaker.
Circuit breaker Amperage
Location
HEATER 30A Fuse box
2. If the reset button is not out, go to Step 2.
3. If the reset button is out, check for a short circuit in the har-
ness. Repair as necessary; then depress the reset button
to reset the circuit breaker.
Step 2
1. Turn the ignition switch ON.
2. Turn the blower switch to the fourth position.
3. Measure the voltage at terminal-wire (L) of the blower mo-
tor connector.
Wire Voltage
Action
(L) 12V Go to Step 3
OV Repair wire harness
(Circuit breaker-Blower motor)
U-7