What was found
DURING GROUND OPERATION WITH THE APU OPERATING, THE FLIGHT CREW DETECTED A STRONG 'HOT SMELL' IN THE CABIN. AFTER A PHONE CONFERENCE WITH HOME BASE MAINTENANCE, THE COOLING TURBINE WAS SUSPECTED. PRESSURIZATION SYSTEM WAS DEFERRED USING M.E.L. PROCEDURES AND ACFT RETURNED TO HOME BASE. FURTHER T/S REVEALED THE GROUND COOLING FAN DID NOT APPEAR TO OPERATE PROPERLY WHICH WOULD CAUSE THE AIR CONDITIONING DISTRIBUTION AND SUPPLY DUCTING'S TEMPERATURE TO INCREASE PRODUCING A 'HOT SMELL'. THE FAN'S CONTROL VALVE WAS CHANGED. THE SYSTEM WAS OPERATED FOR AN EXTENDED PERIOD WITH NO DEFECTS. AIRCRAFT RETURNED TO SERVICE. (X)