A/C Pressure Switch Circuit Troubleshooting
A/C Pressure Switch Circuit Troubleshooting1. Turn the ignition switch ON (II).
2. Turn the blower switch on, and check for blower motor operation.
Does the blower motor run on all speeds ?
YES - Go to step 3.
NO - Troubleshoot the blower motor circuit.
3. Turn the ignition switch OFF.
4. Disconnect heater control panel connector A (14P)
5. Turn the ignition switch ON (II).
6. Measure the voltage between the No.4 terminal of heater control panel connector A (14P) and body ground.
Is there battery voltage ?
YES - Go to step 7.
NO - Go to step 9.
7. Start the engine.
8. Connect the No.4 terminal of heater control connector A (14P) to body ground with a jumper wire.
Does the A/C system come on?
YES - Replace the heater control panel.
NO - Refer to the multiplex control system.
9. Using the Backprobe Set, connect the No.9 terminal of under-dash fuse/relay box connector F (12P) to body ground with a jumper wire.
Does the A/C system come on?
YES - Go to step 10.
NO - Refer to the multiplex control system.
NOTE: Check for multiplex codes in mode 1. Follow the troubleshooting for any codes found. If no codes are found, substitute a known-good multiplex control unit and a ECM one at a time.
10. Disconnect the A/C pressure switch 2P connector and under-dash fuse/relay box connector F (12P).
11. Check for continuity between the No.2 terminal of the A/C pressure switch 2P connector and the No.9 terminal of under-dash fuse relay box connector F (12P).
Is there continuity ?
YES - Go to step 12.
NO - Repair open in the wire between the under-dash fuse/relay box and the A/C pressure switch.
12. Check for continuity between the No.1 and No.2 terminals of the A/C pressure switch.
Is there continuity ?
YES - Repair open in the wire between the heater control panel and the A/C pressure switch.
NO - Go to step 13.
13. Check for proper A/C system pressure.
Is the pressure within specifications ?
YES - Replace the A/C pressure switch.
NO - Repair the A/C pressure problem.