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INSPECTION PROCEDURE 5: The A/C compressor does not work
 
 
 
 
TECHNICAL DESCRIPTION (COMMENT)
When the A/C compressor does not work, the A/C compressor circuit system may be defective.
 
 
 
TROUBLESHOOTING HINT
  • Malfunction of the A/C compressor
  • Malfunction of the A/C compressor relay
  • The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector
  • Malfunction of the ECM
 
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Using scan tool (M.U.T.-IIISE), DTC check.
Check whether the A/C sets a DTC or not.
Is the check result normal?
Go to Step 2.
Refer to DTC chart .
 
STEP 2. Voltage measurement at A/C compressor assembly connector.
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Turn the ignition switch to the "ON" position.
(3) Connect the AC/R terminal of the ECM connector to body ground.
(4) Voltage between power supply terminal and body ground.
OK: The voltage should measure approximately 12 volts (battery positive voltage).
Is the check result normal?
Go to Step 3.
Go to Step 6.
 
STEP 3. Check the A/C compressor.
Refer to .
Is the check result normal?
Go to Step 4.
Replace the A/C compressor.
 
STEP 4. Check the refrigerant level.
Refer to .
Is the refrigerant level correct?
Go to Step 5.
Correct the refrigerant level (Refer to On-vehicle Service ).
 
STEP 5. Replace the A/C-ECU, and then recheck the trouble symptom.
Check that the compressor works normally.
Is the check result normal?
This diagnosis is complete.
Replace the ECM (Refer to GROUP 13A - ECM ).
 
STEP 6. Check the A/C compressor relay.
Refer to .
Is the check result normal?
Go to Step 7.
Replace the A/C compressor relay.
 
STEP 7. Voltage measurement at A/C compressor relay connector.
(1) Remove the relay, and measure at the relay block side.
(2) Voltage between power supply terminal and body ground.
OK: The voltage should measure approximately 12 volts (battery positive voltage).
Is the check result normal?
Go to Step 9.
Go to Step 8.
 
STEP 8. Check of open circuit in A/C compressor relay power supply line between fusible link and A/C compressor relay connector.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
Repair the connector(s) or wiring harness.
 
STEP 9.Check of open circuit in A/C compressor relay power supply line between A/C compressor relay connector and A/C compressor assembly connector.
Is the check result normal?
Go to Step 10.
Repair the connector(s) or wiring harness.
 
STEP 10. Check of open circuit in AC/R line (ECM) between A/C compressor relay connector and ECM connector.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
Repair the connector(s) or wiring harness.