What was found
CONT CAB ZONE TEMP LIGHT ILLUMINATES-RESETS WITH MASTER CAUTION. GROUNDED - YES. INTERROGATED LEFT AND RIGHT PACK ZONE TEMP CONTROLLERS. RIGHT PZTC "FLIGHT DECK TRIM VALVE" FAULT. BITE TEST PASSED. UNABLE TO DUPLICATE WITH APU. 115V AT PLUG D3886 ON THE CONTROL CABIN TRIM AIR VALVE. DUE TO HISTORY, REMOVED AND REPLACED CONT CABIN TRIM AIR VALVE AS A PRECAUTION (V00143) IAW AMM 21-61-21/400. GROUND VERIFICATION TEST IS GOOD. NO LEAKS NOTED.