What was found
CONT CABIN TEMP CONTROLLER IS UNCONTROLLABLE, WILL NOT HOLD TEMP. CONTINUALLY SPIKES IN EITHER DIRECTION. WILL HOLD 22C IN OFF POSITION. GROUNDED - YES. PERFORMED A DUCT TEMPERATURE LIMIT SENSOR TEST REF B737-900 AMM 21-61-04. NO DISCREPANCIES NOTED. RANG OUT S2 (CONT CABIN TEMP SELECTOR) OF THE P5-17 FOR DEAD SPOTS IN THE POT. REF B737-900 WDM 21-61-12 AND 21-61-11. NO DEFECTS NOTED. T/S ON 10-18-22 NOTED THE CONTROL CABIN TCV FAULTING ON A PZTC BITE. REPLACED V143 PER AMM 21-61-21. NO HELP. REPLACED THE #1 PZTC PER AMM 21-61-20. ALL TESTS NORMAL. CONTROL CABIN TEMP CONTROL NOW WORKS NORMALLY. ETOPS GROUND VERIFICATION GOOD.