Cadillac Repair: 2000 DEVILLE DTS, indicator lites, gauge cluster

Question
I HAVE A PROBLEM WITH COMPLETE GAUGE CLUSTER AND ALL A/C INDICATOR LITES NOT LITING UP. BUT A/C WORKS FINE, NO SERVICE LITES,SPEEDO OR TACH DO NOT WORK I"LL LEAVE FOR LUNCH AND ALL WORKS FINE AGAIN FOR WHO KNOWS HOW LONG. IT HAPPENS MAYBE ONCE EVERY 3 MONTHS IF THAT,

Answer
Intermittent problems are extremly hard to diagnose unlees the fault is present at the time the technician has access to the vehicle.

Possible faults:

power supply module for the illumination of the components.

climate control panel.

speedometer cluster assembly.