Resources
Troubleshooting Guide
Diagnose and resolve common fan coil issues with our troubleshooting guides. For detailed procedures, refer to the product IOM manual.
Always disconnect power before servicing. Refer to IOM manual for detailed safety procedures.
Unit Not Heating or Cooling
Possible Causes:
- No water flow to coil - check valves and pump operation
- Incorrect water temperature - verify chiller/boiler settings
- Thermostat not calling for heating/cooling - check setpoint and mode
- Control valve not opening - check actuator and wiring
- Air in coil - bleed air from system
Recommended Action:
Start by verifying water flow and temperature at the fan coil. Check that the thermostat is set correctly and calling for the appropriate mode. Inspect control valve operation and bleed any air from the coil.
Unusual Noise from Fan Coil
Possible Causes:
- Loose components - check fan housing and mounting hardware
- Debris in blower wheel - inspect and clean fan assembly
- Worn bearings - motor may require service or replacement
- Vibration from loose ductwork - secure all connections
- Water hammer in piping - install hammer arrestors
Recommended Action:
Identify the type of noise (rattling, squealing, humming, banging). Rattling usually indicates loose parts. Squealing suggests belt or bearing issues. Humming may be electrical. Banging often relates to water hammer in piping.
Water Leaks or Condensate Issues
Possible Causes:
- Clogged condensate drain - clear drain line and trap
- Improper unit pitch - ensure proper drainage slope
- Damaged drain pan - inspect for cracks or corrosion
- Excessive humidity - check ventilation and dehumidification
- Frozen coil - verify airflow and refrigerant charge (DX units)
Recommended Action:
Check the condensate drain line for clogs or kinks. Verify the unit is properly pitched for drainage. Inspect the drain pan for damage. For persistent issues, consider installing a condensate pump or larger drain line.
Insufficient Airflow
Possible Causes:
- Dirty air filter - replace or clean filter
- Blocked supply or return grilles - remove obstructions
- Dampers closed - check damper positions
- Fan motor failure - verify motor operation
- Incorrect fan speed setting - adjust to proper speed
Recommended Action:
Start with the filter - a dirty filter is the most common cause of poor airflow. Check that all grilles and dampers are open. Verify the fan is operating at the correct speed setting for the application.
Thermostat/Control Issues
Possible Causes:
- Incorrect wiring - verify wiring matches diagram
- Dead batteries (wireless thermostats) - replace batteries
- Thermostat location - avoid drafts and heat sources
- Incompatible thermostat - verify compatibility with unit
- Control board failure - test inputs and outputs
Recommended Action:
Verify thermostat wiring matches the unit wiring diagram. Check that the thermostat is properly configured for the system type. For digital thermostats, verify settings and replace batteries if applicable.
ECM Motor Problems
Possible Causes:
- Incorrect voltage - verify supply voltage matches motor rating
- Communication error - check BACnet/Modbus connections
- Motor overheating - ensure adequate ventilation
- Programming issue - verify speed/CFM settings
- Motor fault codes - consult motor documentation
Recommended Action:
ECM motors require proper voltage and communication setup. Check for fault codes using the motor diagnostic LEDs. Verify programming matches the application requirements. Ensure the motor has adequate cooling.
Need Technical Support?
If troubleshooting doesn't resolve the issue, contact our technical support team or your local Williams representative for assistance.
Phone: (888) 444-1212
Email: EngineeringFanCoil@wfc-fc.com