Honeywell Home PRO 1000 Series Operating Manual page 25

In case of difficulty
If you have difficulty with your thermostat, please try the following suggestions.
Most problems can be corrected quickly and easily.
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• Check circuit breaker and reset if necessary.
• Make sure power switch at heating & cooling system is on.
• Make sure furnace door is closed securely.
• Make sure fresh AAA alkaline batteries are correctly
installed ( see page 9).