These items should be checked at the beginning of each season (or more often if local conditions and usage patterns dictate):
Economizer or Outside Air Damper
Air Filters and Screens
Each unit is equipped with return air filters. If the unit has an economizer, it will also have an outside air screen. If a manual outside air damper is added, an inlet air screen will also be present.
Each of these filters and screens will need to be periodically replaced or cleaned.
RETURN AIR FILTERS
EQUIPMENT DAMAGE HAZARD
Failure to follow this CAUTION can result in premature wear and damage to equipment.
DO NOT OPERATE THE UNIT WITHOUT THE RETURN AIR FILTERS IN PLACE.
Dirt and debris can collect on heat exchangers and coils possibly resulting in a small fire. Dirt buildup on components can cause excessive current used resulting in motor failure.
Return air filters are disposable fiberglass media type. Access to the filters is through the small lift-out panel located on the rear side of the unit, above the evaporator/return air access panel. (See Fig. 3.)
To remove the filters:
To re-install the access panel:
OUTSIDE AIR HOOD
Outside air hood inlet screens are permanent aluminum-mesh type filters. Check these for cleanliness. Remove the screens when cleaning is required. Clean by washing with hot lowpressure water and soft detergent and replace all screens before restarting the unit. Observe the flow direction arrows on the side of each filter frame.
ECONOMIZER INLET AIR SCREEN
This air screen is retained by filter clips under the top edge of the hood. (See Fig. 3.) FIG. 3
MANUAL OUTSIDE AIR HOOD SCREEN
SUPPLY FAN (BLOWER) SECTION
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury or death.
Before performing service or maintenance operations on unit, LOCKOUT/TAG-OUT the main power switch to unit. Electrical shock and rotating equipment could cause severe injury.
Supply Fan (Direct-Drive)
All FC units have the EcoBlue™ direct drive vane axial fan system. The fan is driven by an ECM motor with speed that is user set through the Unit Control Board (UCB). Speeds are fully configurable from 40% to 100% of motor’s maximum speed. See Fig. 5 and 6.
Source: MaintainX (Community Member)