Thermostat Problems and Solutions

Newer thermostats usually have digital displays, which can be used to adjust automated heating and cooling schedules.

Common Problems And Solutions

• Location, location, location... In order to avoid false readings, the thermostat must be installed so that it correctly reads the room temperature. It can't be near a heat source, such as a fireplace, hot water pipes, bright lights, direct sunlight, electrical appliances that produce heat... or in a drafty hallway, or near a window or exterior door that is opened often... or on an outside wall (since outside walls are affected by outside temperatures). Any of these situations may make the thermostat "think" the air in the house is warmer or cooler than it really is.
• Erratic operation or fluctuating temperature can be caused by poor pin connections between the thermostat and the backplate when the backplate is flexed against an uneven wall. Loosening the screws that attached the backplate to the wall should allow the backplate to flatten out. Do this, then snap the thermostat back onto the backplate.
• When a thermostat doesn’t respond to changes in room temperature, it can be a sign that air is passing over the temperature sensor from behind the thermostat. Fix by insulating the hole behind the thermostat with insulation or spray foam.
• Inaccurate temperature means the thermometer needs to be recalibrated. A convenient way to test the temperature sensor is to tape a thermometer to the wall next to the thermostat and wait 15 minutes. Recalibration instructions should have come with the thermostat... they vary by manufacturer.
• Loss of power may be caused by a couple of different things, depending on what controls the thermostat. If the air handler powers the thermostat, check the circuit breaker meant for the air handler and make sure it has not tripped. If batteries power the thermostat, replace them. 

Maintenance

• Give the thermostat's interior a light dusting with a small, soft paintbrush. Canned air can also be used to blow off dust. Twist the screws to remove the cover. Be sure to clean the contacts, which are small metal plates within the unit. The wires coming from the transformer attach to the contacts. Do not touch any of the interior parts with fingers.
• If the base is loose, re-tighten the screws. Check the wires coming from the transformer. If any corrosion is present, remove the wire from the contact and clean it. Use a wire stripper to remove the surrounding insulation, cut back the wire, and reconnect it.
• Make sure the terminal screws are tight.
• For wireless thermostats, make sure the model number of the thermostat matches the model number of the receiver. If the model numbers do not match, the stat and receiver will not be compatible.
• Make sure that your thermostat has been set to the proper position for the season: cooling or heating. The air conditioner will not run with the switch set to "heating" and, conversely, the heating system won't run if the thermostat has been set to "cooling."
• Thermostats that contain a mercury switch must remain perfectly level or they may not control the temperature setting.