As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CABIN AIR TEMP GAUGE FLUCUATES WILDLY IN ALL POSITIONS, TAPPING ON IT CAUSES MAJOR INCREASES. ACFT GROUNDED. REPLACED CABIN TEMP INDICATOR REF 21-61-32-401. OPS CHECK NORMAL. ON THE FOLLOWING FLIGHT, CREW REPORTS CABIN TEMP GAUGE STILL FLUCTUATES =/- 20 C WHEN CHANGING SELECTOR. CONFIRMED FAILURE. REPLACED CABIN TEMP INDICATOR, REF MM 21-61-32. OPS NORMAL.