With RPO C68

1. Check for an open in CLUST Fuse. If open, repair short to ground in CKT 750.
2. Check for an open in ELEC Fuse. If open, repair short to ground in CKT 340.
3. Check for an open in Fusible Element P. if open, repair short to ground in CKT 1440.
4. Check for corrosion on connector terminals at Blower Motor and HVAC Power Module.
5. Make sure ground G222 is clean and tight.
6. If Blower Motor can be controlled in either the Manual mode or the "AUTO" mode but not in both, replace the HVAC Control Assembly.
7. Check if any trouble codes are set by observing if the C or the F is flashing during the first two minutes of operation. If codes are set, refer to the diagnosis in "HVAC: AIR Delivery and Temperature Controls (C-68)," under Air Door Actuator. Testing and Inspection
8. If the steering wheel control functions do not operate but the HVAC Control Assembly functions operate properly, refer to Steering Wheel Controls diagnosis (UK3) under Testing and Inspection.
9. If HVAC Control Assembly does not switch from English to Metric, refer to diagnosis in the Instrument Panel Cluster under Instrument Panel.
10. If Blower runs with the HVAC Control Assembly "OFF," check CKT 65 for a short to Battery.

^ Check for a broken (or partially broken) wire inside of the insulation which could cause system failure hut prove "GOOD" in a continuity/voltage check.
^ Check for proper installation of aftermarket electronic equipment which may affect the integrity of other systems.