As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SUPPLY DUCT AIR TEMP GAUGE READS HIGH AND BOUNCES AROUND WHEN SELECTED TO READ CONTROL CABIN TEMP. AIR TEMPERATURE OPERATES CORRECTLY WHEN CHANGING RHEOSTAT, GAUGE JUST READS HIGH ANYWHERE FROM 40 DEGREES TO 100 DEGREES EVEN WITH COOL AIR BLOWING. ACFT GROUNDED. CONFIRMED, REMOVED AND REPLACED TEMP CONTROL MODULE P5-17 IAW AMM 21-61-15. OPS NORMAL.