Go to the breaker box, and check that the fuse has not blown. (The method will depend on the fuse system for your home.) Many breakers have switches. Open the door to the panel, and examine the fuse diagram on the door. Check to ensure the breaker to the thermostat is in the "On" position.
Grasp the outer edges of the thermostat and pull gently to test the mount. An improperly mounted Honeywell thermostat may not function. If necessary, remount the device. If it feels loose, pull off the outer cover on the thermostat to expose the mounting panel and wall plate. Tighten any loose screws.
Examine the furnace or air-conditioning unit for an "On/Off" switch, which may resemble a light switch and sit on the surface of the unit. Check to ensure all doors are closed on the device. If unsure whether the heating or cooling unit is functioning, call a service technician for maintenance.
Look at the reading on the thermostat to determine the temperature of the room. Set the thermostat appropriately based on room temperature. For example, if you set the temperature at 75 degrees but the room temperature reads 74 degrees, the unit will not turn on. For heat, you must set the temperature set on the Honeywell higher than the room temperature; for cooling, you must set it lower.
Press the "Menu" button on the Honeywell thermostat if the device is digital. Look for a security setting that allows for locking the unit. If the unit is locked, you cannot set it. Check the manual for instructions to unlock the system.
Turn the thermostat off completely. The method will depend on the model. Wait five minutes, and turn the Honeywell thermostat back on. This action may reset the device.
- Honeywell offers many models of thermostats, both manual and digital. Check the user's guide that came with your unit for more troubleshooting suggestions.