Troubleshooting a Blank Thermostat

Blank Thermostat

First let's discuss the basics.

A thermostat is defined as a device that automatically regulates temperature, or that activates a device when the temperature reaches a certain point. (Oxford Languages)

The recommended settings for a thermostat is to have the device on and set to "Cool" or "Heat" mode on the display screen.  The fan should be set to the AUTO position or displaying "Fan Auto" on the display screen.  

If you do not see anything on your display screen, this is signifying that there is an issue going on with your thermostat or HVAC system.

No worries, there are some things you can troubleshoot before reaching out to your HVAC company.

Here's a list of some common reasons as to why a TSTAT is blank:

Is the thermostat in the "On" position?

  • Check the settings and make sure someone did not turn it off without you knowing.

Is it time to change batteries?

  • Not all thermostats have batteries but depending on how your thermostat is wired and what model thermostat you have, your TSTAT batteries may have died. To Check them, you simply pull the thermostat straight off the wall.  On the back side of the thermostat is where you will find batteries, if equipped with them. Try replacing the batteries with lithium batteries.  Instantly, your thermostat's display should light up.  If this resolves your issue, simply press the thermostat back onto the wall.

Did the breaker trip in your breaker box?

  • Locate your breaker box and search for the breakers labeled for your AC system.  Ensure they are in the "On" position.  Breakers trip for various reasons like power surges, multiple appliances running at once, or there may be an underlying issue going on with your HVAC system.  If the AC breakers are off, flip the switch "On" and check your thermostat.  If your thermostat display did not turn on, then you should call a professional AC company to evaluate and diagnose any shortages on your HVAC system.

When is the last time you changed filters or had an AC tune up?

  • Make sure your filters are clean.  Look at your float switch located on the air handler near the drain line.  If there is water standing in the pipe, this means your condensate drain is clogged.  Go outdoors and use a wet/dry vacuum on the condensate drain PVC-pipe located near your condenser unit.  Vacuum the pipe for roughly 1-2 minutes and turn off.  If your thermostat display is now on, your house should start to cool down.  If this did not work, the pipe may need to be chemically cleaned by a professional.  It's recommended to have an annual maintenance performed at least once per year, and required by manufacturers to keep your HVAC warranty in good standing.