CPR SMT DOOR WARNING LIGHT CAME ON AT FL290. PLT BROUGHT THE CABIN ALT UP TO ABOVE ALT WHERE O2 MASKS DEPLOYED AS HE DSNDED. FINALLY FIGURED OUT IT WAS JUST A FALSE WARNING AND CONTINUED.

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WHILE FLYING AT FL290 THE CABIN DOOR LIGHT CAME ON; CABIN PRESSURE STAYED AS SET BUT I ASKED CENTER FOR LOWER; HE GAVE ME 210. JUST IN CASE IT WAS SOMETHING OTHER THAN THE LIGHT I TURNED THE PRESSURIZATION CTLR TO BRING THE CABIN ALT UP; IF DOWN. THE ONLY PROBLEM WAS WHEN I DID; I SET IT TO 12500. WHEN IT REACHED 12500 IN THE CABIN; THE CABIN ALT LIGHT CAME ON AND THE O2 MASK IN THE BACK DEPLOYED. I WAS ALARMED AND THOUGHT I MAY REALLY HAVE A PROBLEM. I DID NOT REALIZE I BROUGHT THE CABIN UP SO MUCH. THEN I TOLD CENTER I HAD PRESSURIZATION TROUBLE. HE ASKED IF I WAS DECLARING AN EMER. I SAID NO; BUT WANTED LOWER AND TO GO INTO WACO. HE GAVE 11000 AND DIRECT WACO. WHEN I GOT TO FL190; I SAW THE CABIN WAS HOLDING ALT AND SET IT LOWER. I WAS SURE THE ONLY PROBLEM I HAD WAS A BAD SWITCH AND ONLY THE DOOR LIGHT. I ELECTED TO CLB AND GO THE DALLAS ADS TO THE MANUFACTURER'S PLACE. HE GAVE ME HIGHER AND CLRED ME AS REQUESTED. IF I PAID MORE ATTN TO THE PRESSURIZATION CTLR CABIN ALT; I WOULD HAVE MADE SURE IT WASN'T AT 12500. I KNEW WHAT HAPPENS WHEN THE CABIN REACHES 12500. IN TRAINING YOU LEARN A GREAT DEAL MORE ABOUT SYS THAN MOST PEOPLE THINK. I KNOW FL290 IS NOT THE PLACE TO WAIT AND SEE IF IT IS ONLY A DOOR LIGHT. THE CTLRS ALWAYS WORK VERY WELL WITH THE PLTS. EVEN THOUGH I DIDN'T DECLARE AN EMER; HE DIDN'T HESITATE TO GIVE ME A NEW CLRNC.