What was found
PRIOR TO DEPARTURE, GOT A CABIN DOOR ANNUNCIATOR & RED 6 PACK LIGHT. BOTTOM ROW MIDDLE LIGHT FOR THE VENT DOOR. COMPLIED WITH MEL O PROCEDURES MEL 52-70-01-06. RESETTING VENT DOOR IAW MEL & CONFIRMING ALL 9 FLAGS. ON CLIMB OUT NOTICED THAT CABIN MATCHED OUR RATE OF CLIMB & CABIN PARTIAL PRESSURIZED. GOT TO ALTITUDE OF 12,500FT WITH A CABIN ALTITUDE OF 9,000. DESCENDED TO 10,000FT CABIN PRESSURE STABILIZED AT 7,000FT WITH A DIFFERENTIAL PRESSURE OF 1.1 PSID. RETURNED TO DEPARTURE AIRPORT, AFTER LANDING SHUT DOWN WITH APU ON CABIN DOOR MOTOR CB TRIPPED. REMOVED & INSTALLED NEW SOLENOID IAW AMM 52-10-00 OPS CHECKED GOOD. ALSO REMOVED & INSTALLED NEW SWITCH IAW AMM 52-70-00 OPS CHECKED GOOD