What was found
TAIL COMPARTMENT TEMP HI ON AT 200 AFTER TAKEOFF. APU WAS RUNNING WITH AIR OFF. COMPLIED WITH QRH 21.4, LIGHT WENT OUT AFTER 1:15 DURING STEP 5. REFERENCE WO 00258905, PERFORMED TASK CARD 21-059-005, FOUND CLAMP LT HEAT EXCHANGER CLAMP LEAK RE-SECURED.