Honeywell thermostats are designed to keep your home at a steady temperature by automatically turning on a fan to pump either hot or cold air throughout the house. The unit is controlled from a single wall-mounted panel. If your thermostat stops responding to manual input or will not turn on automatically when the temperature falls outside the desired range, there are a number of things you can try before having your unit professionally serviced.
Press the "Menu" button on the control panel, then select "Security Settings."
Press "Change Lock Mode," then follow the on-screen prompts to set your level of access. Select "Unlocked." If the unit is locked, the temperature cannot be changed, which may keep the fan from turning on.
Press "System" and select "Heat" or "Cool" mode as needed. Even if the current temperature is below the desired temperature, the fan will not start if it is in "Cool" mode. Likewise, the fan will not start even if it is too hot if the thermostat is in "Heat" mode.
Check your circuit breaker and reset or replace any fuses as needed. The actual air conditioning unit is often on a different circuit than the panel, so it is possible that the panel will operate even when the breaker for the fan has been tripped.
Check the power switch on the actual air conditioning unit, and turn it on if it is off. The fan may be set to "Off" even while the panel is active.
Press firmly on the furnace door to ensure it is tightly shut. The fan will not turn on if the door is even partially open.
Check the panel. If "Waiting for Equipment" is on the screen, the system is automatically restarting. Wait five minutes, then try to activate the fan again.