Magnetic Clutch Does Not Operate - Mazda MX-5 1990 Workshop Manual

, TROUBLESHOOTING GUIDE
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Symptom: Magnetic clutch does not operate.
Note
• If the blower motor also does not operate, see "Blower motor does not operate"; page U-7.
Normal operation of magnetic clutch
The magnetic clutch is supplied with battery voltage as shown:
1. A/C and blower switches are turned ON.
2. ECU receives signal that AIC and blower switches are ON and creates ground circuit.
3.
A/C relay is magnetized and contact is closed.
4. Battery voltage is applied to magnetic clutch and clutch locks.
Note
• The ECU also controls the additional fan and magnetic clutch operation depending on engine
load. (Refer to Section F.)
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WIPER 20A
FUSE BOX
AD FAN 20A
MAIN FUSE BLOCK
05UOUX·084
05UOUX·013
05UOUX-011
Step 1
1 . Check the following fuses.
Fuse Amperage
Location
WIPER 20A In fuse box
AD FAN 20A In main fuse block
2. If the fuses are OK, go to Step 2.
3. If a fuse is burned, check for a short circuit in the harness
before replacing
it.
Step 2
1. Run the engine at idle.
2. Turn the
A/C
switch and blower switch ON.
3. Measure the voltage at terminal-wire (B/R) of the magnetic
clutch connector.
Wire
Voltage
Action
(B/R)
12V
Go to Step 3
OV.
Go to Step 5
Step 3
1. Disconnect the thermoswitch connector.
2. Check for continuity of the thermoswitch.
Continuity Action
Yes Go to Step 4
No
Replace thermoswitch
U-9