OPERATION
- The battery voltage is applied to the A/C compressor relay (terminal No. 4).
- The battery voltage is applied to the A/C compressor relay (terminal No. 3) from the ignition switch. The engine-A/T-ECU (terminal No. 21) makes the power transistor in the unit be in "ON" position and makes currents go on the A/C compressor relay coil, and that makes the relay be in "ON" position.
- When the A/C compressor is in "ON" position, the battery voltage is supplied to the A/C compressor (terminal No. 1) from the A/C compressor relay (terminal No. 1).
FUNCTION
- When the A/C switch "ON" signal is input to the engine-A/T-ECU, the engine-A/T-ECU places the A/C compressor relay in the ON position. Accordingly, the battery voltage supplied to the A/C compressor operates the magnet clutch.
PROBABLE CAUSE
- Failed A/C compressor relay
- Failed A/C compressor magnet clutch
- Open/short circuit in A/C compressor relay circuit or loose connector contact
- Failed engine-A/T-ECU
)
Q: Is the check result normal?
YES:
Go to Step 2 
.NO: Repair.
- Remove relay, and measure at relay box side.
- Ignition switch: ON
- Voltage between terminal No. 3 and earth.
OK: System voltage
Q: Is the check result normal?
YES:
Go to Step 5 .NO: Go to Step 4
.)
Q: Is the check result normal?
YES:
- Check intermediate connectors C-106, C-202 and C-203, and repair if necessary. If intermediate connectors are normal, check and repair harness between B-18X (terminal No. 3) A/C compressor relay connector and C-303 (terminal No. 4) ignition switch connector.
- Check power supply line for open or short circuit.
- Remove relay, and measure at relay box side.
- Voltage between terminal No. 4 and earth.
OK: System voltage
Q: Is the check result normal?
YES:
Go to Step 6 .NO:
- Check intermediate connector A-14, and repair if necessary. If intermediate connector is normal, check and repair harness between B-18X (terminal No. 4) A/C compressor relay connector and battery.
- Check power supply line for open/short circuit.
)
)
Q: Is the check result normal?
YES:
Go to Step 7 .NO: Repair.
- Disconnect connector, and measure at harness side.
- Remove B-18X (terminal No. 1 and No. 4) A/C compressor relay and short-circuit of harness side connector.
- Ignition switch: ON
- Voltage between terminal No. 1 and earth.
OK: System voltage
Q: Is the check result normal?
YES:
Go to Step 8 .NO:
- Check and repair harness between B-27 (terminal No. 1) A/C compressor connector and B-18X (terminal No. 1) A/C compressor relay connector.
- Check output line for open/short circuit.
)
- Measure engine-A/T-ECU terminal voltage.
- Ignition switch: ON
- Voltage between terminal No. 21 and earth.
OK: System voltage
Q: Is the check result normal?
YES:
Go to Step 12 .NO: Go to Step 9
.
Q: Is the check result normal?
YES:
Go to Step 10 .NO: Repair.
- Check earthing line for open circuit and damage.
Q: Is the check result normal?
YES:
Go to Step 11 .NO: Repair.
STEP 11. MUT-II/III data list
- Item 49: A/C relay
- Engine: Idling
- A/C set temperature:
- Maximum Cool when temperature in cabin is
25°C or more - Maximum Hot when temperature in cabin is
25°C or less
OK:
- ON (when A/C is ON)
- OFF (when A/C is OFF)
Q: Is the check result normal?
YES:
Intermittent malfunction (Refer to GROUP 00 -
How to Use Troubleshooting/Inspection
Service Points 
).NO: Replace engine-A/T-ECU.
Q: Is the check result normal?
YES:
Go to Step 13 .NO: Repair.
- Check earthing line for damage.
Q: Is the check result normal?
YES:
Go to Step 14 .NO: Repair.
Q: Is the check result normal?
YES:
Go to Step 15 .NO: Repair.
NOTE: Before checking harness, check intermediate connectors C-106, C-202 and C-203, and repair
if necessary.
- Check power supply line for damage.
Q: Is the check result normal?
YES:
Go to Step 16 .NO: Repair.
NOTE: Before checking harness, check intermediate connector A-14, and repair if necessary.
- Check power supply line for damage.
Q: Is the check result normal?
YES:
Go to Step 17 .NO: Repair.
- Check output line for damage.
Q: Is the check result normal?
YES:
Replace A/C compressor magnet clutch.NO: Repair.