What temperature ranges are acceptable for heating and cooling on the TH6220D?
For heating, the acceptable range is 40°F to 90°F (4.5°C to 32°C). For cooling, the acceptable range is 50°F to 99°F (10°C to 37°C). Make sure temperature settings are within these ranges if they are not changing properly.
From the official Honeywell T6220D Programmable Thermostat manual, page 18
Have a follow-up question?
Answers from the official manual.
Common questions