Possible Cause: System has not been balanced.
Corrective Action: Request a copy of the balance report and review against the specified CFM requirements.
Possible Cause: The filter is dirty.
Corrective Action: Replace the filter.
Possible Cause: The coil is dirty.
Corrective Action: Clean the coils. Brushes, water, cleaning solutions designed for HVAC coils, and air are acceptable cleaning methods. Do not use a pressure washer.
Possible Cause: A blockage exists in the system.
Corrective Action: Verify that all dampers are open. Check for restrictions in the ductwork.
Possible Cause: System losses are greater than design.
Corrective Action: Adjust or change sheaves or replace motor as necessary based on the system losses as installed.
Possible Cause: Fan speed is lower than design, belt slipping, or wrong sheaves.
Corrective Action: Adjust the belt and sheaves as necessary for the installed conditions.
Possible Cause: Fan is running backwards.
Corrective Action: Switch two legs of power at unit main power supply (all unit components are phased at the factory).
Possible Cause: VFD requires adjustment.
Corrective Action: Check fan set points. Adjust PID settings for desired performance.