Actually, that fault is b74. This unit must have been manufactured between March 1, 1997 and April 21, 1997. During that time period, they had a bug in the software for the CLD. It should read "Cond Fan Vari Speed Fault Ckt 2". The fan inverter is in a fault and needs to be checked.
KIT06170 is a replacement eprom kit for the clear language display to resolve the unknown diagnostic.