As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EQUIP COOLING VALVE LIGHT CYCLED ON AND OFF CONTIUOSLY. REPLICATED FAULT WITH SWITCH IN STANDBY POSITION AND T-SHOT TO FAULTY OVERBOARD EXHAUST VALVE CLOSED POSITION DEMAND. REPLACED OVERBOARD EXHAUST VALVE REF AMM 21-58-05 AND ACP''D POST INSTALLATION TEST WITH NO FURTHER FAULTS. SYSTEM NOW OK. PARTS USED: 76-2125-9-0001,QTY :1 1775851,QTY :1 ROTABLE PARTS CHANGE WAS INDICATED - TT # 1775851 SN OFF 0592.