GMC Chevrolet Silverado 2500HD 2021 Owner's Manual page 202

Dual Automatic Climate Control System
The heating, cooling, and ventilation in the vehicle can be controlled with this system.
1. Driver and Passenger Temperature
Controls
2. MAX Defrost
3. Air Delivery Mode Controls
4. A/C (Air Conditioning)
5. SYNC (Synchronized Temperature)
6. Recirculation
7. Power Button
8. Fan Control
9. Rear Window Defogger (If Equipped) or
Heated Mirrors (If Equipped)
10. AUTO (Automatic Operation)
Climate Controls
Climate Control Display
1. Driver and Passenger Temperature
Settings
2. Fan Control
3. Driver and Passenger Temperature
Controls
4. Sync (Synchronized Temperature)
5. Recirculation
6. Air Delivery Mode Controls
7. Auto (Automatic Operation)
8. A/C (Air Conditioning)
9. On/Off (Power)
201