VAV-SVX01C-EN 73
Troubleshooting
VAV Series Fan Failure Procedures
In the event that the fan output is not energizing, properly inspect the following:
1. Verify the output configuration in the UCM setup menu.
• Unit needs to be configured as Series fan
2. Outputs on the UCM are configured as normally closed
• Verify the output configuration in the UCM setup menu.
Note: Series fan powered units in the occupied mode has the fan continuously energized. See
operation Chapter for details
3. Tracer Summit has the fan output disabled
• Check group, global, and/or Tracer 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 or Rover has released fan disable override.
5. If VAV UCM is calling in the status menu for the Fan to be on and it is not then check UCM Triac
output wiring; and Relay output.
• Override damper open
• See if fan cycles on
• Check J8 to TB1-2. Should have 24 VAC; if it does not, measure the power input to TB1-
1 (power) and TB1-2 (ground) of the UCM board. The supply voltage should be between
20 and 28 VAC (24 VAC cataloged). However, voltages at either extreme may result in
system instability.
• Triac can be checked with purchasing a 24 VAC LED and see if it lights up on call for fan
UCM if LED does not light up replace UCM
• Remove fan wires from UCM and apply 24 VAC directly to fan relay wires.
• Fan relay should energize. If it does not check wiring. If wiring is OK replace fan relay.
Notice:
UCM Outputs are switched to ground. Do not jumper 24 VAC to J9, J10, or J11 because damage
will occur.
6. After all checks have been completed, check motor fan winding integrity and bearing failure.
VAV Parallel Fan Failure Procedures
In the event that the fan output is not energizing, properly inspect the following:
1. Verify the output configuration in the UCM setup menu.
• Unit needs to be configured as parallel fan
2. Outputs on the UCM are configured as normally closed
• Verify the output configuration in the UCM setup menu.
Note: Parallel fan can be enabled by either a differential temperature above the heating
setpoint or CFM flow. See “UCM Programming and Operation,” p. 30 for details.
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