carrier aircon unit

[hotrock]

Hi

Problem with this unit.
It has to be switched off at the fuse board, but everything works properly, but when switched off at the master control, the fan in the unit keeps moving slowly and making a deep humming noise, so there is still power going to the fan.
Any ideas?

Thanks

[Electrocoolman]

Hi.,
Some manufacturers units, when in cooling mode, continue running the indoor unit fan for a set time, when the unit is switched off. This is to 'dry' the evaporator coils.

Don't know about the humming.

[paul_h]

Fan relay is stuffed I think. Fairly common in units with solid state relays, they fail but still pass some current through to the fan, making it run slowly and hum.
Otherwise it could be a welded mech relay and a faulty fan motor and/or capacitor.