The way a heat pump thermostat should be repaired is determined by the cause of the malfunction. A thermostat that doesn’t efficiently control the temperature may need to be cleaned. Repositioning the unit on the wall or relocating the unit may also fix the problem.
To fix a heat pump thermostat that displays an incorrect temperature, turn the power to the heating system off, and remove the cover of the thermostat. Use a soft brush or a vacuum with a brush attachment to remove any dust or dirt that has accumulated in the unit. The thermostat may contain two parallel metal bars inside the unit that needs to be wiped off with a soft cloth. Check for any corrosion, and remove it using an electronic contact cleaner.
A thermostat that is not electronic or programmable must be mounted level on the wall in order to work properly. Use a bubble level to check that the thermostat is mounted level on the wall. It should also be mounted approximately 5 feet from the floor in a location that allows the unit to sense an air sample that gives an accurate representation of the room's temperature. A thermostat that is mounted in a corner, behind a door, in a closet, near a window or door, or near a heat source should be moved to ensure that it detects the room's temperature accurately.