Tips & Resources

Why is My Thermostat Not Working? Common Thermostat Problems and How to Troubleshoot the Issue

Thermostats are often the overlooked components of a home’s HVAC system. When the furnace or air conditioning is not working properly, the thermostat is rarely the first thing people check. The reality is, the thermostat is a complex piece of equipment and, if installed incorrectly or not properly maintained, it can cause issues with your heating and cooling systems.

Here are some tips for troubleshooting problems with a thermostat.

Where is it located?

To work properly, the thermostat should be positioned five feet from the ground and away from direct sunlight and heat sources of any kind. This includes heating vents and appliances that give off heat. Similarly, the thermostat should not be impacted by drafts from windows or doors.

Is it level?

Houses shift and settle over time. As a result, the thermostat may no longer be level. If the unit is tilted or slanted, it may not function properly. Older mercury bulb thermostats are especially impacted by this because the thermometer inside needs to be level to operate correctly.

How old is the thermostat?

Thermostats don’t last forever and like any mechanical equipment, the older it is, the more likely it is to break. Newer programmable thermostats work well and make efficient HVAC performance simple to maintain.

Is the power on? Does it need batteries?

Without power, the thermostat is not monitoring the temperature and sending the right messages to the HVAC system. Make sure the thermostat is connected to power and all the connections are tight. If it runs on batteries, it may need fresh ones.

Does it need cleaning? Are there loose or corroded wires?

Dust and dirt can cause the thermostat to malfunction. To clean it, turn off the power to the unit, remove the cover and gently dust the components with a soft brush and slide a slip of paper between the contacts. Check the wires. Tighten any loose ones and replace any that are corroded.

Is it programmed correctly? Is it on the correct “heat” or “cool” setting?

Thermostats can inadvertently be switched to the wrong setting or the programming could be off.

Is it installed correctly?

DIY thermostat installation is not recommended. If your thermostat was installed by the previous homeowner, it is possible that it is wired incorrectly or has loose wires.

Does the furnace/air conditioner kick on when the temperature is raised/lowered five degrees?

Your HVAC system should respond relatively quickly with a temperature setting change of five degrees or more. If this does not happen, the issue could be the thermostat.

Thermostat repair and installation is best left to professionals. Contact a Rheem Pro Partner for thermostat trouble or for any HVAC issues or questions. We serve customers throughout Colorado and Wyoming.