What was found
WHILE SITTING AT GATE ON APU BLEED AIR, FLIGHT DECK TEMP GOT VERY HOT. TURNED TEMP CONTROL DOWN AND TEMP INITIALLY DIDN'T CHANGE, INDICATION STAYED VERY HOT. AFTER APPROX TWO MINUTES, TEMP RETURNED TO NORMAL. WHILE HOT, LEFT PACK SHOWED APPROX 60 DEG C. GROUNDED - YES. FOUND L/H PACK DISCHARGE TEMP BULB & BOSS DISCONNECTED FROM MIX MANIFOLD DUCT. ACCOMP EA 800-21EA-23413 TO RE-ATTACH TEMP BULB TO MIX MANIFOLD LK & OPS NORMAL. CONTROL CABIN TEMP OPS NORMAL.