What was found
IN CRUISE AT 26000' WE GOT AN AMBER R HYD TEMP HIGH MSG. SHORTLY FOLLOWED BY A CYAN CAS MISCOMPARE MSG. THE LEFT MFD HYD PG SHOWED RIGHT HYDRAULIC SYSTEM GREEN 100C. THE LEFT MFD HYD PG SHOWED AMBER 100C. RAN THE QRH AND DECLARED THE EMERGENCY. WHEN DESCENDING THE TEMP CAME DOWN AND MSGS CLEARED. SUBSEQUENT LANDING WAS UNEVENTFUL. "CORRECTIVE ACTION" REMOVED RH HEAT EXCHANGER BYPASS VALVE AND REPLACED WITH CUSTOMER SUPPLIED NEW VAVLE. PERFORMED SYSTEM TEAK, BLEED AND OPERATIONAL CHECK, NO DEFECTS NOTED. SERVICED HYDRAULIC TO FULL. RAN ENGINES AND CYCLE FLIGHT CONTROLS AND RH TEMPERATURE REACH AROUND 52. WORK PERFORMED IAW CL-350 AMM 29-12-45.