Mazda Mazda6 Workshop Manual Supplement page 375

NO.24 A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY
24 A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY
• A/C compressor magnetic clutch does not disengage.
DESCRIPTION
• A/C compressor magnetic clutch stuck engagement
• A/C relay is stuck closed
• Improper A/C compressor magnetic clutch clearance
POSSIBLE
• Short to GND circuit between A/C switch and PCM
CAUSE
• Short to GND circuit between A/C relay and PCM
• A/C relay to magnetic clutch circuit shorts to battery power
Diagnostic Procedure
STEP INSPECTION
1 Perform self-test function using WDS or
equivalent.
Turn engine switch to ON.
Retrieve any DTC.
Is DTC displayed?
2 Start engine and run it at idle.
Turn A/C switch on.
Remove A/C relay.
Does A/C magnetic clutch disengage?
3 Start engine and turn A/C switch on.
Measure PCM terminal 84 voltage while
disconnecting refrigerant pressure switch
connector.
Note
• PCM terminal 84 voltage should read B+
when disconnecting connector. If PCM
terminal 84 voltage reading remains
below 1.0 V, short to GND circuit may be
present.
Is voltage B+?
4 Reconnect refrigerant pressure switch
connector.Measure PCM terminal 84 voltage
while turning off A/C switch.
Note
• PCM terminal 84 voltage should read B+
when turning A/C switch off. If PCM
terminal 84 voltage reading remains
below 1.0 V, short to GND circuit maybe
present.
Does voltage remain B+?
5 Verify test results.
• If okay, return to diagnostic index to service any additional symptoms.
• If malfunction remains, replace PCM. (See
End Of Sie
TROUBLESHOOTING
RESULTS
Yes DTC is displayed:
Go to appropriate DTC test.
Communication error message is displayed:
Inspect for following:
• Open circuit between PCM control relay and PCM
• Open circuit PCM control relay and PCM terminal
• PCM control relay stuck open
• Open or poor GND circuit (PCM terminal 65, 85,
• Poor connection vehicle body GND
No No DTC is displayed:
Go to appropriate DTC test.
Yes Inspect for following:
• A/C relay is stuck closed
• Short to GND circuit between A/C relay and PCM
If both items are okay, go to next step.
No Inspect if circuit between A/C relay and magnetic
clutch shorts to battery power circuit.
If circuit is okay, inspect magnetic clutch stuck
engagement or clearance.
Yes Inspect for short to GND circuit between refrigerant
pressure switch and PCM terminal 84.
No Go to next step.
Yes Inspect for following:
• Short to GND circuit between A/C switch and A/C
• Short to GND circuit between A/C amplifier and
No Inspect for stuck closed A/C switch.
F2–64 PCM REMOVAL/INSTALLATION)
ACTION
terminal 53 or 79
69
103 or 104)
terminal 73
amplifier.
refrigerant pressure switch.
A6E408018881226
F2
F2–223