Trane DFIA Programming Manual page 33

FAULT CODE: Unit off/Fan on
MUA-SVP01A-EN • Direct-Fired Indoor and Outdoor Units
Diagnostics
PROBLEM: The controller has not activated the unit enable output to start the
fan, but the fan status input, is receiving a signal that the fan is running. This fault
will automatically clear about 15 seconds after the fault is corrected.
SOLUTION: If fan is running
1. Is controller unit enable output LED for lit?
– Yes. There is a problem with the controller program. Call factory.
– No. Continue.
2. Is controller output contact for the unit enable output closed?
– Yes. Turn off the power to the controller and recheck. If contact is still
closed the controller output is shorted. Replace the controller.
– No. Continue.
3. Is the unit enable relay energized?
– Yes. There is a short or jumper in the wiring. Determine cause and rectify.
– No. Continue.
4. Is motor starter energized?
– Yes. There is a short or jumper in the wiring. Determine cause and rectify.
– No. Continue.
5. Is the fan status relay energized?
– Yes. There is a short or jumper in the wiring. Determine cause and rectify.
– No. Continue.
6. Is the fan status relay's normally open contact, closed?
– Yes. Replace relay.
– No. Continue.
7. Is there continuity between at the controller between the fan status
terminals?
– Yes. There is a short in the wiring between these terminals. Determine
cause and rectify.
– No. Replace controller.
SOLUTION: If fan is not running
1. Is the fan status relay's normally open contact, closed?
– Yes. Replace relay.
– No. Continue.
2. Is there approximately 5VDC at both controller terminals used for the fan
status?
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