Ignition Key On, engine off Push and hold the fan up arrow & fan down arrow at the same time. After about 5 seconds, the LCD where your temp/fan speed is displayed will show "-00". Push the fan "AUTO" button, and the LCD will display any fault codes stored in the programmer.
Fault Code Description
00 no faults detected
01 Temp Door Motor Circuit Failure
02 Temp Door Motor Circuit Failure
03 Ambient Sensor Open
04 Ambient Sensor Short
05 In-Car Temp Sensor Open
06 In-Car Temp Sensor Short
07 Solar Load Sensor Open
08 Solar Load Sensor Short
09 Low freon detected
10 or --- UART Failure
Push any lower button (ie vent, heater, AUTO, etc) to exit the diagnostic
mode.
FYI, pushing the fan up arrow or down arrow while in diagnostic mode, followed by fan AUTO, allows you to check other parameters as well. However, I'd need a few more pages to explain everything.
Jim Mason
90 L98 - 6 spd - Z51