Inspection Procedure 31: A/C Compressor Relay System

OPERATION

Battery voltage is applied to the A/C compressor relay (terminal No. 1).
The battery voltage is applied to the A/C compressor relay (terminal No. 4) from the ignition switch.
Engine-ECU (terminal No. 95) applies current to the A/C compressor relay coil by turning ON the power transistor in the unit in order to turn the relay ON.
When the A/C compressor relay turns ON, battery voltage is supplied by the A/C compressor relay (terminal No. 4) to the A/C compressor (terminal No. 1).

FUNCTION

When the A/C switch ON signal is input into the engine-ECU, the engine-ECU turns ON the A/C compressor relay. This causes battery voltage to be supplied to the A/C compressor assembly and the A/C compressor clutch actuates.

PROBABLE CAUSES

Failed A/C compressor relay
Failed A/C compressor assembly
Open/short circuit or harness damage in the A/C compressor relay circuit, or loose connector contact.
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-207 A/C compressor relay connector

Q. Is the check result normal?

Go to Step 2 .

Repair or replace the connector.

STEP 2. Check A/C compressor relay itself.

Check A/C compressor relay itself (Refer to GROUP 55A - On-vehicle Service - Relay Check ).

Q. Is the check result normal?

	Go to Step 3 .

	Replace the A/C compressor relay.

STEP 3. Perform voltage measurement at B-207 A/C compressor relay.

Disconnect connector, and measure at J/B side.
Voltage between terminal No. 3 and earth.

OK: System voltage

Q. Is the check result normal?

Go to Step 4 .

Check power supply line for open/short circuit.

STEP 4. Check harness between battery and B-207 (terminal No. 3) A/C compressor relay connector.

note

Before checking harness, check intermediate connectors B-231, B-118, B-212 and B-208, and repair if necessary.

Check power supply line for damage.

Q. Is the check result normal?

Go to Step 5 .

Repair the damaged harness wire.

STEP 5. Perform voltage measurement at B-207 A/C compressor relay.

Disconnect connector, and measure at harness side.
Voltage between terminal No. 1 and earth.

OK: System voltage

Q. Is the check result normal?

Go to Step 7 .

Go to Step 6 .

STEP 6. Connector check: B-240 ignition switch connector

Q. Is the check result normal?

Check power supply line for open/short circuit.

Repair or replace the connector.

STEP 7. Check harness between B-240 (terminal No. 4) ignition switch connector and B-207 (terminal No. 1) A/C compressor relay connector.

note

Before checking harness, check intermediate connectors B-231 and B-230, and repair if necessary.

Check power supply line for damage.

Q. Is the check result normal?

Go to Step 8 .

Repair the damaged harness wire.

STEP 8. Connector check: A-09 engine-ECU connector

Q. Is the check result normal?

Go to Step 9 .

Repair or replace the connector.

STEP 9. Perform voltage measurement at A-09 engine-ECU connector.

Disconnect connector, and measure at harness side.
Voltage between terminal No. 95 and earth.

OK: System voltage

Q. Is the check result normal?

Go to Step 10 .

Check signal line for open/short circuit.

STEP 10. Check harness between B-207 (terminal No. 2) A/C compressor relay connector and A-09 (terminal No. 95) engine-ECU connector.

note

Before checking harness, check intermediate connectors B-231 and B-118, and repair if necessary.

Check signal line for damage.

Q. Is the check result normal?

Go to Step 11 .

Repair the damaged harness wire.

STEP 11. Connector check: A-124 A/C compressor assembly connector

Q. Is the check result normal?

Go to Step 12 .

Repair or replace the connector.

STEP 12. Check harness between B-207 (terminal No. 4) A/C compressor relay connector and A-124 (terminal No. 1) A/C compressor assembly connector.

note

Before checking harness, check intermediate connectors B-231, B-118 and A-13, and repair if necessary.

Check power supply line for open/short circuit and damage.

Q. Is the check result normal?

Go to Step 13 .

Repair the damaged harness wire.

STEP 13. Check harness between B-207 (terminal No. 1) A/C compressor relay connector and B-27 diode.

note

Before checking harness, check intermediate connectors B-231 and B-118, and repair if necessary.

Check power supply line for short circuit.

Q. Is the check result normal?

Go to Step 14 .

Repair the damaged harness wire.

STEP 14. Check A/C compressor clutch operating conditions.

Disconnect A-09 engine-ECU connector, and short-circuit terminal No. 95 to the earth.

OK: A/C compressor clutch operates.

Q. Is the check result normal?

	Replace the engine-ECU.

	Replace the A/C compressor assembly.