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Honeywell T8400C1099 Owner's Manual

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  Summary of Contents for Honeywell T8400C1099

  • Page 1 Electronic Thermostat Room SYSTEM OWNER’S GUIDE Cool Off Heat Auto On 69-1491–1 69-1491-1...
  • Page 2 Congratulations on the purchase of your new thermostat! Over 100 years of Honeywell engineering expertise went into the making of this thermostat in an effort to provide you with a more comfortable and convenient living environment. • Simple and easy to use . The ▲ and ▼ keys make it easy for you to change your temperature setting.
  • Page 3: Setting Fan And System Switches

    Settings Setting FAN and SYSTEM Switches Fan and system settings are controlled by using FAN and SYSTEM switches located on the bottom of the thermostat case. First set the FAN switch: Auto: Normal setting for most homes. In cooling, the fan goes off and on with the cooling equipment.
  • Page 4 Then set the SYSTEM switch: Cool: Normal setting for months when your home needs cooling (air conditioning). Digital display shows a snowflake when cooling is on. Off: Both heating and cooling are off. Heat: Normal setting for months when your home needs heating.
  • Page 5 Displaying Temperature Setting NOTE: Your temperature setting can be set anywhere from 40° to 99°F (5° to 37°C). The temperature setting and the room temperature are shown separately on the digital display. The ▼ indicator points to Set when the temperature setting is displayed and to Room when the room temperature is displayed.
  • Page 6: Changing Temperature Setting

    Changing Temperature Setting 1. To lower the temperature setting, press the ▼ key. When in the heating mode, lowering the temperature at night or during the day can lower your energy costs. Room M18442 2. To raise the temperature setting, press the ▲ key. When in the cooling mode, raising the temperature before you leave for work or school also lowers your energy costs.
  • Page 7: Troubleshooting Guide

    Troubleshooting Guide CAUTION Operating at too low of an outdoor temperature may cause compressor damage. Damage to compressor possible. Do not operate cooling if outdoor temperature is below 50°F (10°C). Refer to manufacturer’s recommendations. Heating or cooling does not come on. •...
  • Page 8 Temperature setting is too warm or cool • Adjust the temperature by pressing either the ▲ or ▼ key. If you have questions concerning this thermostat, call Honeywell Customer Assistance at 1-800-468-1502. Automation and Control Solutions Honeywell Honeywell Limited- Honeywell Limitée...