Mazda MX-6 1998, Workshop Manual

Page: 372 / 1282

TROUBLESHOOTING [ENGINE CONTROL KL]
24
A/C ALWAYS ON/A/C COMPRESSOR RUNS CONTINUOUSLY
DESCRIPTION
A/C compressor magnetic clutch does not disengage
POSSIBLE
CAUSE
• Short to ground between A/C switch and PCM through
• Short to ground circuit between A/C relay and PCM
• A/C relay to magnet clutch circuit shorts to battery power
• Stuck engagement
• A/C relay stuck to close
STEP
INSPECTION
ACTION
1 Retrieve and record any continuous memory,
KOEO and KOER DTCs.
Are there any DTCs displayed?
Yes Go to appropriate DTC test.
No Go to next step.
2 Start engine and run it at idle.
Turn A/C switch on.
Remove A/C relay.
Does A/C magnet clutch disengage?
Yes Check following:
A/C relay stuck closed.
Short to ground circuit between A/C relay and PCM.
If both items okay, go to next step.
No Check if circuit between A/C relay and magnet clutch
shorts to battery power circuit.
If circuit is okay, check for stuck to engage magnet clutch.
3 Connect NGS tester to DLC.
Access ACCS PID on NGS tester.
Start engine and turn A/C switch on.
Read ACCS PID while disconnecting high
pressure switch connector.
Note
• ACCS PID should read OFF when
disconnecting connector. If ACCS PID
reading remains ON, short to ground circuit
may be present.
Does ACCS PID reading remain on?
Yes Check for short to ground circuit between high pressure
switch and PCM.
No Go to next step.
4 Reconnect high pressure switch connector.
Read ACCS PID while disconnecting low
pressure switch connector.
Note
• ACCS PID should read OFF when
disconnecting connector. If ACCS PID
reading remains ON, short to ground circuit
may be present.
Does ACCS PID reading remain on?
Yes Check for short to ground circuit between low pressure
switch and high pressure switch.
No Go to next step.
5
Reconnect low pressure switch connector.
Read ACCS PID while turning off A/C switch.
Note
• ACCS PID should read OFF when turning
A/C switch OFF. If ACCS PID reading
remains ON, short to ground circuit may be
present.
Does ACCS PID reading remain on?
Yes Check for short to ground circuit between low pressure
switch and A/C switch.
No Check for A/C switch stuck closed.
6
Verify test results. If okay, return to diagnostic index to service any additional symptoms.
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