Component Inspection

Component Inspection

1. Reconnect A/C pressure sensor and ECM connectors.
2. Set up an oscilloscope as follows :
Channel A (+): terminal 2 of the A/C pressure sensor (back probe), (-): ground
3. Start the engine to normal operating temperature and Measure voltage between terminal 2 of the A/C pressure sensor harness Connector (back probe) and chassis ground.
A. Specification:
Approx. below 1.3 - 1.5V at A/C OFF with idle
Approx. above 1.5V at A/C ON with idle




4. Is voltage within the specification ?
YES
1) Check for poor connection between ECM and component: backed out terminal, improper mating, broken locks or poor terminal to wire connection. Repair as necessary and go to "Verification of Vehicle Repair" procedure
NO
1) Go to next step as below
5. Return vehicle to original condition
6. Ignition "ON" & Engine "OFF"
7. Is the A/C compressor clutch engaged ?
YES
1) Disconnect A/C clutch relay and check the A/C compressor clutch status.
- If engaged, repair open/short circuit in the A/C compressor clutch harness or replace faulty compressor clutch assembly. And go to "Verification of Vehicle Repair" procedure
- If disengaged, repair open/short circuit in the A/C clutch relay harness or replace faulty clutch relay. And go to "Verification of Vehicle Repair" procedure
NO
1) Go to next step as below
8. Start the engine to normal operating temperature.
9. Turn the A/C ON and OFF
10. Does the A/C compressor clutch cycle ON and OFF with the selector switch ?
YES
1) Check A/C pressure sensor for contamination, deterioration, or damage. Substitute with a known-good A/C pressure sensor and check for proper operation. If the problem is corrected, replace A/C pressure sensor and then go to "Verification of Vehicle Repair" procedure
NO
1) Monitor the "A/C SWITCH & A/C COMPRESSOR" parameters on the Scantool data list. Refer to "Signal Waveform & Data" in the "General Information" procedure.
- Turn the A/C ON and OFF
- Check the scantool indicate when the A/C is ON and OFF correctly.
If OK, check the A/C pressure. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
If NG, repair the signal from the A/C selector switch and compressor switch. Go to "Verification of Vehicle Repair" procedure