What was found
IAD/DTW - FLT 6426 - DURING TAXI-OUT AT 0745 HOURS ON 7-1-97, EXPERIENCED A RT DUCT OVERTEMP LIGHT ILLUMINATION. AIRCRAFT RETURNED TO THE GATE WHERE THE MAINTENANCE TECHNICIANS TROUBLESHOT THE DISCREPANCY AND FOUND THE RT PACK OVERTEMP WOULD NOT RESET. MAINTENANCE OPENED A DEFERRED MAINTENANCE ITEM NR 57360 IAW WITH ALL MAINTENANCE PROCEDURES. MAINTENANCE CLOSED DMI 57360 ON 7-2-97 BY REMOVING AND REPLACING TEMP CONTROL VALVE, OPS CHECK OK. AIRCRAFT RELEASED AND APPROVED FOR RETURN TO SERVICE. (X)