Expert: Tom Joy - 9/3/2007

Question
HAVE A 1996 SEDAN DEVILLE,CAB BLOWER FAN WON'T WORK,BLOWER MOTOR HAS 12V ON TERMINAL C AND A GOOD GROUND ON TERMINAL A. TERMINAL B STAYS AT A CONSTANT 12V REGARDLESS WHAT SPEED THE FAN IS SET ON.I HAVE TWO CODES IN SYSTEM PO603 AND AC1347 THAT IS CURRENT.THE PROGRAMMER WAS REPLACED ABOUT 5 YEARS AGO.
THANKS IN ADVANCE FOR YOUR HELP, EDDIE

Answer
Replace the blower motor.

NOTE: whenever you replace the blower motor you should also replace the ACM as the motor tends to wear out the internal brushes and puts a heavy amperage draw against the ACM and burns out the diodes.

You can try a blower motor FIRST and see if it works.