What was found
DESCENDING THROUGH 18000 FT, ACM OVERTEMP AND EMER PRESS ANNUNCIATORS ILLUMINATED. AFTER 15 SECONDS, BOTH CLEARED. CABIN HAD SMALL AMOUNT OF SMOKE AND CLEARED AS WELL. OPERATED CABIN AND COCKPIT ENVIRONMENTAL SYS IN AUTO AND MANUAL 1 HOT AND COLD USING APU AND THEN WITH BOTH ENGINES OUT 90 DEGREES N. CABIN AND COCKPIT TEMPS REACTED NORMALLY. MAX SUPPLY TEMPS WERE 235 DEGREES, NO ODOR NOTED. INSP AND FOUND DUCTS IN TAILCONE TO HAVE NO LEAKS. REF MM 21-10-00 21-21-02 FOR WORK. NO CAS MESSAGES POSTED.