tep-by-Step Checklist Proper maintenance ensures efficiency, longevity, and air quality in FCU systems. Follow this comprehensive guide for residential, commercial, and industrial FCUs. 📌 Monthly Maintenance (Basic Checks) 📌 Quarterly Maintenance (Intermediate Checks) 📌 Annual Maintenance (Professional Servicing) ⚠️ Common FCU Problems & Fixes Issue Likely Cause Solution Weak Airflow Clogged filter/dirty coil Clean/replace filter