Why does one outdoor fan shut off in heat cycle?

[JCole21961]

I have two Hitachi 5T heat pumps. Each outdoor unit has two fans. One of these is controlled by a pressure switch and shuts off at times. Why is this? I would think the unit needs all the air possible in order to extract as much heat as possible. Note that this is not the defrost mode when both fans stop.

[Tayters]

Don't know about the specifics of a Hitachi but older Fujitsu's I seem to recall would do it so as to control the temperature of the indoor coil. If indoor coil was getting too hot (over 60*C roughly) outdoor fan would slow down to reduce capacity then stop if coil temp got to a certain level.

Cheers,
Andy.

[JCole21961]

In this case there is no temperature sensor on the indoor coil. The fan is controlled by a pressure switch on the refrigerant line. I'm not sure if it on the high or low side. I cannot see any reason to shut down one fan except for defrost, when both stop.

[frank]

In this case there is no temperature sensor on the indoor coil. The fan is controlled by a pressure switch on the refrigerant line. I'm not sure if it on the high or low side. I cannot see any reason to shut down one fan except for defrost, when both stop.

it's called superheat control