GMC 2015 Sierra Owner's Manual page 24

Climate Control System (with Air Conditioning)
1. Fan Control
2. A/C (Air Conditioning)
3. Air Delivery Mode Control
4. Defrost
5. TEMP (Temperature Control)
6. Air Recirculation
K
7. Rear Window Defogger
(If Equipped)
f
Outside Heated Mirror
(If Equipped)
Outside Air (If Equipped)
In Brief 1-17