Have a malfunctioning thermostat? Smart thermostats play a very important role in maintaining our indoor comfort. But just like any technological equipment, they are not immune to glitches and malfunctions that can leave us without our AC in the SWFL heat. Understanding the common thermostat issues and having the knowledge to troubleshoot them can be the key to keeping your home’s climate just the way you like it.

Whether you’re grappling with a thermostat that seems to have a mind of its own or facing a blank display that leaves you in the dark about your home’s temperature, we’ve got you covered. Here we’ll review the most common issues that can happen with a faulty thermostat and how to fix them so you can troubleshoot on your own. Remember, anytime you’re dealing with loose wires or any mechanical components or electrical components involved in your thermostat or HVAC unit in general, it’s best to contact an HVAC professional who is trained and certified to handle these components safely.

9 Common Malfunctioning Thermostat Issues and How to Fix Them

Thermostat issues can lead to heating or cooling problems in your home. Here are some common reasons smart thermostats and older thermostats may be acting up and ways to fix them:

1. Thermostat Displays the Wrong Temperature

Fix: Calibrate the thermostat or change the location of your thermostat to a position away from drafts, heat sources, or direct sunlight for more accurate temperature readings.

2. Thermostat Not Responding

Fix: Check the power source. Replace dead batteries if it’s battery-powered, or check the circuit breaker or look for a blown fuse if it’s hardwired. Ensure there is no loose wiring.

3. Heating or Cooling System Not Turning On

Fix: Confirm that the thermostat temperature setting is set to the desired temperature. Check the circuit breaker to make sure it hasn’t tripped. Inspect the wiring for loose connections.

4. Short Cycling (Turning On and Off Frequently)

Fix: Clean or replace the air filter. Ensure that the thermostat is away from heat sources, and check for any obstructions in the thermostat’s location.

5. Thermostat Display Blank or Display Not Working

Fix: Check the power source (batteries or wiring). Replace batteries if necessary. If it’s a wiring issue, consult a professional.

6. Thermostat Running on the Wrong Schedule

Fix: Double-check the programmable thermostat settings. If it’s a smart thermostat, ensure that it is connected to the Wi-Fi and has the correct time and schedule settings.

7. Thermostat Temperature Swings (Varies Widely From Set Point)

Fix: Calibrate the thermostat, and consider adjusting the anticipator setting if it’s a mechanical thermostat. Check for drafts or heat sources affecting temperature readings.

8. Thermostat Compatibility Issues (New Thermostat Not Working With Existing Air Conditioner)

Fix: Ensure that the thermostat is compatible with your heating and cooling system. Check wiring compatibility, and consult the thermostat manual or a professional if needed.

9. Faulty Temperature Sensors

Fix: If possible, replace the sensor. If it’s an integral part of the thermostat, you may need to replace the entire unit.


If you’re having issues with a digital thermostat, there is usually a simple solution to the common problems we see. Still, if none of these fixes work or you have an outdated thermostat that needs to be replaced, call a professional HVAC technician at Dolphin Cooling and Heating. We’re here for all your HVAC equipment repair, regular maintenance, and replacement needs.