I have read of some folks making moderately extensive mods in some
Foresters to improve that function. I dunno if they apply to your model
or not. The system in both my soobs works quite well most of the time.
It does occasionally want to turn the A/C compressor on when it isn't
needed for cooling OR defrosting and I just turn it off manually.

Carl

What do you mean by 'The temp overshoots far from the set point '? Are
you saying that the temperature in the car goes higher than what the
temperature is set up for? How do you know? Most auto climate control
systems are constantly adjusting, as the interior temperature (at
wherever the sensors are) is constantly changing. It's not like a
house, which is well insulated and has much less glass area.

Dan D
'99 Impreza 2.5 RS (son's)
Central NJ USA

One other thing that could cause some problems. There is a solar
'detector' on top of the dash (on one of my cars it is in the center,
the other near the passenger side - both forward near the windshield
base. make sure you do not have papers or a dash cover or other item
covering it. The system uses it to alter A/C compressor usage based on
incoming light.

good luck

Carl