Troubleshooting - Honeywell RTH6400 Series Quick Installation Manual

Advanced Installation Guide

Troubleshooting

Troubleshooting
If you have difficulty with your thermostat, please try
the following suggestions.
Most problems can be corrected quickly and easily.
Display is blank • Make sure fresh AA alkaline
Temperature
settings do not
change
Cannot change
system setting
to Cool
Fan does
not turn on
when heat is
required
69-2210ES—05
batteries are correctly installed
(see page 7).
Make sure heating and cooling
temperatures are set to acceptable
ranges:
• Heat: 40° to 90°F (4.5° to 32°C).
• Cool: 50° to 99°F (10° to 37°C).
• Check Function 1: System Type to
make sure it is set to match your
heating and cooling equipment
(see page 14).
• Check Function 3: Heating Fan
Control to make sure it is set to
match your heating equipment (see
page 16).
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