( TF09E8KG10100012062FAAT00 )
A/C Pressure Switch Circuit Troubleshooting
HVAC Control (Lever type)
NOTE:
  • Do not use this troubleshooting procedure if any of these items are working properly with the A/C switch ON; condenser fan, radiator fan, A/C compressor, or if the heater does not work. Refer to the symptom troubleshooting index.
  • Check the A/C high-side pressure.
  1. Disconnect the A/C pressure switch 2P connector.
  1. Turn the ignition switch to ON (II).
  1. Measure the voltage between the A/C pressure switch 2P connector No. 2 terminal and body ground.
Is there battery voltage?
YES -
Go to Step 4 .
NO -
Go to Step 20 .
  1. Turn the ignition switch to LOCK (0).
  1. Check for continuity between the No. 1 and No. 2 terminals of the A/C pressure switch.
Is there continuity?
YES -
Go to Step 6 .
NO -
Replace the A/C pressure switch.■
  1. Reconnect the A/C pressure switch 2P connector.
  1. Disconnect the A/C switch 5P connector.
  1. Turn the ignition switch to ON (II).
  1. Measure the voltage between the A/C switch 5P connector No. 2 terminal and body ground.
Is there battery voltage?
YES -
Go to Step 10 .
NO -
Repair open in the wire between the A/C pressure switch and the A/C switch.■
  1. Turn the ignition switch to LOCK (0).
Is the A/C switch OK?
YES -
Go to Step 12 .
NO -
Replace the A/C switch.■
  1. Disconnect the heater fan switch 8P connector.
  1. Check for continuity between the A/C switch 5P connector No. 1 terminal and the heater fan switch 8P connector No. 6 terminal.
Is there continuity?
YES -
Go to Step 14 .
NO -
Repair open in the wire between the A/C switch and the heater fan switch.■
Is the heater fan switch OK?
YES -
Go to Step 15 .
NO -
Is the evaporator temperature sensor OK?
YES -
Go to Step 16 .
NO -
  1. Jump the SCS line with the HDS.
    NOTE: This step must be done to protect the engine control module (ECM)/powertrain control module (PCM) from damage.
  1. Disconnect ECM/PCM connector A (49P).
  1. Check for continuity between the following terminals of ECM/PCM connector A (49P) and the evaporator temperature sensor 2P connector.
    49P:
    2P:
    No. 10
    No. 2
    No. 38
    No. 1

Is there continuity?
YES -
Go to Step 19 .
NO -
Repair open in the wire(s) between the ECM/PCM and the evaporator temperature sensor.■
  1. Check for continuity between ECM/PCM connector A (49P) No. 38 terminal and body ground.
Is there continuity?
YES -
Repair short to body ground in the wire between the ECM/PCM and the evaporator temperature sensor.■
NO -
Check for loose wires or poor connections at ECM/PCM connector A (49P), the evaporator temperature sensor 2P connector, the A/C pressure switch 2P connector, the A/C switch 5P connector and at the heater fan switch 8P connector. If the connections are good, substitute a known-good ECM/PCM, and recheck. If the symptom/indication goes away, replace the original ECM /PCM.■
  1. Turn the ignition switch to LOCK (0).
  1. Reconnect the A/C pressure switch 2P connector.
  1. Make sure the A/C switch is OFF.
  1. Turn the ignition switch to ON (II).
  1. Measure the voltage between under-dash fuse/relay box connector A (36P) No. 21 terminal and body ground with the under-dash fuse/relay box connectors connected.
Is there battery voltage?
YES -
Repair open in the wire between the A/C pressure switch and the MICU.■
NO -
Check for loose wires or poor connections at the under-dash fuse/relay box. If the connections are OK, substitute a known-good MICU and recheck. If the symptom goes away, replace the original MICU .■
HVAC Control (Push button type)
NOTE:
  • Do not use this troubleshooting procedure if any of the following items are operative; condenser fan, radiator fan, A/C compressor, or if the heater is inoperative. Refer to the symptom troubleshooting index.
  • Check the A/C high-side pressure.
  1. Turn the ignition switch to ON (II).
  1. Check if the blower motor operates at all speeds.
Does the blower motor operate at all speeds?
YES -
Go to Step 3 .
NO -
  1. Turn the ignition switch to LOCK (0).
  1. Disconnect the HVAC control unit 12P connector.
  1. Turn the ignition switch to ON (II).
  1. Measure the voltage between the HVAC control unit 12P connector No. 3 terminal and body ground.
Is there battery voltage?
YES -
Go to Step 13 .
NO -
Go to Step 7 .
  1. Turn the ignition switch to LOCK (0).
  1. Disconnect the A/C pressure switch 2P connector.
  1. Turn the ignition switch to ON (II).
  1. Measure the voltage between the A/C pressure switch 2P connector No. 2 terminal and body ground.
Is there battery voltage?
YES -
Go to Step 11 .
NO -
Go to Step 23 .
  1. Check for continuity between the No. 1 and No. 2 terminals of the A/C pressure switch.
Is there continuity?
YES -
Go to Step 12 .
NO -
Replace the A/C pressure switch.■
  1. Check for continuity between the HVAC control unit 12P connector No. 3 terminal and the A/C pressure switch 2P connector No. 1 terminal.
Is there continuity?
YES -
Check for loose wires or poor connections at the HVAC control unit 12P connector and at the A/C pressure switch 2P connector.■
NO -
Repair open in the wire between the HVAC control unit and A/C pressure switch.■
  1. Turn the ignition switch to LOCK (0).
  1. Disconnect the heater fan switch 8P connector.
  1. Disconnect the HVAC control unit 12P connector.
  1. Check for continuity between the HVAC control unit 12P connector No. 8 terminal and the heater fan switch 8P connector No. 6 terminal.
Is there continuity?
YES -
Go to Step 17 .
NO -
Repair open in the wire between the HVAC control unit and heater fan switch.■
  1. Disconnect the evaporator temperature sensor 2P connector.
  1. Jump the SCS line with the HDS.
    NOTE: This step must be done to protect the engine control module (ECM)/powertrain control module (PCM) from damage.
  1. Disconnect ECM/PCM connector A (49P).
  1. Check for continuity between the following terminals of ECM/PCM connector A (49P) and the evaporator temperature sensor 2P connector.
    49P:
    2P:
    No. 10
    No. 2
    No. 38
    No. 1

Is there continuity?
YES -
Go to Step 21 .
NO -
Repair open in the wire(s) between the ECM/PCM and the evaporator temperature sensor.■
  1. Check for continuity between ECM/PCM connector A (49P) No. 38 terminal and body ground.
Is there continuity?
YES -
Repair short to body ground in the wire between the ECM/PCM and evaporator temperature sensor.■
NO -
Go to Step 22 .
Is the evaporator temperature sensor OK?
YES -
Check for loose wires or poor connections at ECM/PCM connector A (49P). If the connections are good, check the ECM/PCM grounds. If the grounds are good, substitute a known-good ECM/PCM, and recheck. If the symptom/indication goes away, replace the original ECM/PCM. ■
NO -
Replace the evaporator temperature sensor .■
  1. Turn the ignition switch to LOCK (0).
  1. Reconnect the A/C pressure switch 2P connector.
  1. Make sure the A/C switch is OFF.
  1. Turn the ignition switch to ON (II).
  1. Measure the voltage between under-dash fuse/relay box connector A (36P) No. 21 terminal and body ground with the under-dash fuse/relay box connectors connected.
Is there battery voltage?
YES -
Repair open in the wire between the A/C pressure switch and the MICU.■
NO -
Check for loose wires or poor connections at the under-dash fuse/relay box. If the connections are OK, substitute a known-good MICU and recheck. If the symptom goes away, replace the original MICU .■