MUA-SVP01A-EN • Direct-Fired Indoor and Outdoor Units 33
Diagnostics
FAULT CODE: Unit off/Fan on
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?