As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BOI- STRONG MILDEW OR FUNGUS ODOR NOTICED INSIDE AIRCRAFT DURING DESCENT. MAINTENANCE REPLACED THE NR 1 AND NR 2 RECIRCULATION FAN FILTERS IAW AMM 21-22-12. CHECKED ACM WATER SEPARATORS FOR PLUGGED LINES, NONE FOUND. OPERATED APU FOR BLEED AIR, NO ODOR IN CABIN NOTICED. AIRCRAFT RETURNED TO SERVICE.