I have a Unitary Products HVAC home unit and the A/C fan does not always come on when thermo kicks on, even though the condenser is running.
Sometimes the fan does not shut off when unit is shut off.
I suspect the control board is TU (bad). It is a 031-01267-001 per the PL.
Where can these be purchased? Is this the probable cause of this irregular operation? (i.e maybe a sticking relay on the circuit board/control board)?
Thanks

Check all thermostat wiring especially the G wire for the fan blower circuit.
It could be a relay on the board but good luck finding that relay.
Boards are expensive so I would make sure all wiring on the board/thermostat wires are good before replacing. I have no idea if you will need a different harness with the new style board. Best to ask them when ordering.

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PartsGuy.com -- 031-01267-001 Control Module