Installation and Maintenance Manual

VAV-SVX07A-EN 81
Troubleshooting
Notice:
Equipment Damage!
The Tracer UC400 controller outputs are switched to ground. Do not jumper 24 VAC to Binary
output TRIAC(s) because damage will occur.
6. After all checks have been completed, check motor fan winding integrity and bearing failure.
VAV Parallel Fan Failure Troubleshooting Procedures
WARNING
Hazardous Service Procedures!
The maintenance and troubleshooting procedures recommended in this section of the manual
could result in exposure to electrical, mechanical or other potential safety hazards. Always refer
to the safety warnings provided throughout this manual concerning these procedures. When
possible, disconnect all electrical power including remote disconnect and discharge all energy
storing devices such as capacitors before servicing. Follow proper lockout/tagout procedures to
ensure the power can not be inadvertently energized. When necessary to work with live
electrical components, have a qualified licensed electrician or other individual who has been
trained in handling live electrical components perform these tasks. Failure to follow all of the
recommended safety warnings provided, could result in death or serious injury.
In the event that the fan output is not energizing, properly inspect the following:
1. Verify the output configuration in the Tracer UC400 controller setup screen.
• Unit needs to be configured as parallel fan.
2. Outputs on the Tracer UC400 controller are configured as normally closed.
• Verify the output configuration in the Tracer UC400 controller setup screen.
Note: Parallel fan can be enabled by either a differential temperature above the heating
setpoint or CFM flow. See Operation chapter for details.
3. Tracer SC has the fan output disabled.
• Check overrides to make sure they are not inhibiting fan operation.
4. A flow override exists locking out the fan output.
• Check to make sure Tracer SC or Tracer TU has released fan disable override.
Note: If fan cycling is based on temperature go to step 5 and if it is based on air flow go to step
6.
5. If fan control is based on temperature and zone temperature is at or above the heating setpoint
plus heating offset on units configured as temperature control. A factory set differential of 0.5°F
exists to prevent short cycling.
• Increase the Tracer UC400 controller heating setpoint causing fan to be cycled on.
• Lower the heating setpoint by 6 degrees and the fan should cycle off.
6. If the fan control is based on flow, the unit fan will be energized whenever supply airflow is
below this setpoint. For this parallel fan configuration, the fan control point, if specified in a
percentage of unit airflow, must be set between 15% and 30% of the units cataloged airflow to
assure proper operation. A differential of 5% exists to avoid excessive fan cycling.
• Override damper closed until CFM is below enabled flow setpoint.
• See if fan cycles on.
• Override damper open until CFM is above enabled flow setpoint fan should cycle off.
7. If the Tracer UC400 controller is calling in the status screen for the fan to be on and it is not then
check the Tracer UC400 controller TRIAC output, wiring, and relay output.