FLC OF A B727 EXPERIENCED A LOSS OF CABIN PRESSURIZATION AND DECLARED AN EMER TO DSND AND DIVERT TO LAND. PAX MASKS DROPPED WHEN CABIN REACHED 14000 FT. CREW HAD ALREADY DONNED OXYGEN MASKS PRIOR TO EMER DSCNT.

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CLBING THROUGH FL356; #3 BLEED TRIP OFF LIGHT ILLUMINATED AND ASSOCIATED BLEED VALVE CLOSED. CAPT CONFIRMED CABIN ALT STABLE (APPROX 100-300 FPM ROC); REQUESTED DSCNT FROM ATC; XFERRED CTLS TO FO AND BEGAN WORKING ON CHKLIST TO RESOLVE PROB WITH SO. WITHIN 45-60 SECONDS OF FIRST LIGHT; L AIR CONDITIONING PACK OVERHEATED (DESPITE SO'S ATTEMPT TO CTL IT BY GOING TO MANUAL AND SELECTING A WARMER TEMP) AND THE PACK TRIPPED. WITHOUT EVEN LOOKING; I COULD TELL WE WERE IN A RAPID DEPRESSURIZATION (PHYSICAL SYMPTOMS). CAPT IMMEDIATELY CALLED FOR OXYGEN MASKS AND EMER DSCNT. HE DECLARED AN EMER; COORDINATED DSCNT WITH ATC AND WORKED ON CHKLISTS; WITH SO. DECISION TO DIVERT TO LNK VICE DEST (DSM) MADE DUE TO FUEL STATE AND DOUBTS REGARDING PRESSURIZATION (SO HAD REGAINED CTL BY FOLLOWING CHKLISTS). LANDED WITH 11800 LBS OF FUEL. NO PAX OR CREW RPTING ILL-EFFECTS. (OXYGEN MASKS HAD DEPLOYED AT 14000 FT CABIN ALT. HAVE NO IDEA HOW HIGH THE CABIN ALT ACTUALLY GOT.) AFTER LNDG; #3 BLEED TRIP LIGHT AGAIN ILLUMINATED; COULD NOT RESET. NO RECOMMENDATIONS FOR PREVENTION. A MECHANICAL PROB IN TWO BAD PLACES ON THE PRESSURIZATION SYS COMPOUNDED TO MAKE A WORSE SCENARIO.