Is it normal for both cooling fans to constantly run when the climate control is on defrost? The AC is not on and they run as soon as you start it and don't shut off. It will also do it when the climate control is set to mix defrost and lower vents. Also when they run the idle drops a little. If he puts the control panel to any other setting that doesn't have defrost, they immediately turn off.

Fans run when the A/C compressor is running on the turbo models IIRC. I know '04 WRX does that.. The N/A cars will use an algorythim to turn fans on if the A/C compressor is running.

 

A/C compressor runs in defrost settings

^^^ what he said - newer cars climate systems will always use the a/c compressor/evaporator coil to help 'dehumidify' when defrost is selected.