There Is No Power From a Home Thermostat

Thermostat Settings

• Inadvertently changing the thermostat’s settings may prevent it from coming on. Many thermostats have two separate setting controls. On one side, there is a “heat,” “air” and an “off” setting. Make sure that either the “heat” or the “air” setting is selected. On the other side of the thermostat, there is an “auto” and an “on” setting. If the “auto” setting is selected, the thermostat does not activate the system unless the programmed temperature is at least 3 degrees higher than the temperature in the house.

Thermostat Battery

• The thermostat’s battery may also be the culprit. All thermostats don’t have batteries, but in those that do, the system does not engage if the batteries are not charged. Replacing the batteries should resolve this problem and restore the thermostat to a functional status.

Breaker or Fuse

• The thermostat may not be operating because of a breaker or fuse problem. Some homes have breaker boxes while others utilize fuse boxes. If the HVAC breaker is tripped or the HVAC fuse is blown, there is no power to the thermostat. A breaker can be reset by turning it completely off and then turning it back on. However, a blown fuse must be replaced.

Emergency Shut Off Switch

• The thermostat’s lack of power may be due to the deactivation of the emergency shut off switch. Many homes have a shut off switch that is located either on or near the furnace and is similar to a light switch. If the switch is off, turning it back on should restore power to the thermostat. In addition, some homes have a cut-out switch for the furnace door, and for safety reasons, the switch cannot be activated unless the furnace’s door is completely closed.