1. Check the No. 36 (10 A) fuse in the under-dash fuse/ relay box.
Is the fuse OK? YES-Go to step 2.
NO-Replace the fuse, and recheck. If the fuse blows again, check for a short in the No. 36 (10 A) fuse circuit.
2. Disconnect the recirculation control motor 7P connector.
3. Turn the ignition switch ON (II).
4. Measure the voltage between the recirculation control motor 7P connector terminal NO.1 and body ground.
Is there battery voltage? YES-Go to step 5.
NO-Repair open in the wire between the No. 36 (10 A) fuse in the under-dash fuse/relay box and the recirculation control motor.
5. Turn the ignition switch OFF.
6. Test the recirculation control motor.
Is the recirculation control motor OK? YES-Go to step 7.
NO-Replace the recirculation control motor, or repair the recirculation control linkage or door.
7. Disconnect the HVAC control unit 28P connector.
8. Check for continuity between body ground and the HVAC control unit 28P connector terminals No. 21 and No. 22 individually.
Is there continuity? YES-Repair short to body ground in the wire(s) between the HVAC control unit and the recirculation control motor.
NO-Go to step 9.
9. Turn the ignition switch ON (II), and check the same terminals for voltage to body ground.
Is there any voltage? YES-Repair short to power in the wire(s) between the HVAC control unit and the recirculation control motor. This short may also damage the HVAC control unit. Repair the short to power before replacing the HVAC control unit.
NO-Go to step 10.
10. Turn the ignition switch OFF.
11. Check for continuity between the following terminals of the HVAC control unit 28P connector and the recirculation control motor 7P connector.
28P:
No.21
No.22
7P:
No.7
No.5
Is there continuity? YES-Check for loose wires or poor connections at the HVAC control unit 28P connector and at the recirculation control motor 7P connector. If the connections are good, substitute a known-good HVAC control unit, and recheck. If the symptom/ indication goes away, replace the original HVAC control unit.
NO-Repair open in the wire(s) between the HVAC control unit and the recirculation control motor.
HVAC Control Power and Ground Circuit Troubleshooting
1. Check the No. 36 (10 A) fuse in the under-dash fuse/ relay box.
Is the fuse OK? YES-Go to step 2.
NO-Replace the fuse, and recheck. If the fuse blows again, check for a short in the No. 36 (10 A) fuse circuit.
2. Disconnect the HVAC control unit 28P connector.
3. Turn the ignition switch ON (II).
4. Measure the voltage between the HVAC control unit 28P connector terminal No. 27 and body ground.
Is there battery voltage? YES-Go to step 5.
NO-Repair open in the wire between the No. 36 (10 A) fuse in the under-dash fuse/relay box and the HVAC control unit.
5. Turn the ignition switch OFF.
6. Check for continuity between the HVAC control unit 28P connector terminal No. 18 and body ground.
Is there continuity? YES-Check for loose wires or poor connections at the HVAC control unit 28P connector. If the connections are good, substitute a known-good HVAC control unit, and recheck.
NO-Check for an open in the wire between the HVAC control unit and body ground. If the wire is OK, check for poor ground at G503.