What was found
(CAN) CREW CALLED TO REPORT THAT AFTER DEBOARDING PAX, THEY STARTED THE APU & AFTER 2 MINUTES THEY STARTED SMELLING A BURNING - HEAT TYPE SMELL & THE CABIN TEMPERATURE STARTED CLIMBING VERY HOT WHICH THEY COULD NOT CONTROL - THEY STARTED THE ENGINES THINKING THAT MAYBE THEY HAD AN APU PROBLEM BUT THIS DID NOT CHANGE THE SITUATION. AIRC CYLCLE MACHINE SEIZED. AIR CYCLE MACHINE REPLACED.