The MU-2 has a pressurized Cabin. To adjust the Cabin Pressure look at the Copilots Side, the Instruments underneath the Yoke. At the Air Cond Panel there are Bleed Air at the left and Cabin Temperature at the right. Temperature is on Auto. In XP, Passengers couldn't complain. The rest of the Controls on the Air Cond Panel are in Default Position.
For Take Off, Engine Start and Shutdown, set Bleed Air to Off. After Take Off and in stable Climb, set Bleed Air to Both. In case of a lost Engine, set Bleed Air to the running Engine. You need Bleed Air On for the Cabin Pressure.
The Instrument in the Middle is the Control for the Cabin Pressure. With the Cabin Alt Knob on the right Side, you set your Cabin Altitude. If you go over 12000 feet, set your Cabin Pressure to 10000. The Instruments on the right shows your Cabin Pressure, the Difference between Cabin and Outside Pressure and how fast the Cabin Pressure is changing if you set a new Pressure.
For Example. My longer Flights are mostly at a Altitude of 15000 Feet. Bleed Air is Off until I reach a Altitude between 3000 and 5000 Feet. You can switch it On earlier but for Take Off, you will Full Power. Now I also set the Cabin Pressure to 10000 Feet. That's all.
For Descent, I slowly set the Cabin Pressure back after reaching 10000 Feet. Set it at least to 1000 Feet above Airport Altitude. Before reaching Final Approach, I depressurize the Cabin - Cabin Altitude to 0. It may not be the correct Procedure for real Life Operations, but my Passengers are very brave and silent.
If you forget to set Cabin Pressure and going to High, there will be a Master Caution Warning and an Indication Light at the Annunciation Panel.