Blank Display on Thermostat Problem - bad tstat
Blank Display on Thermostat Problem - Screen Disappeared - The thermostat display is our interface with our HVAC equipment. The display lets us know what the temperature is in the house. The display tells us what the desired settings are including letting us know the set point setting for the temperature. Some displays give us the time and the newer modern displays show us family photos like a screensaver on our computer. But what happens when the display is not there or there is a blank thermostat display or no display on the thermostat? Is it a bad thermostat or something else that caused the display to disappear?

Blank Display on Thermostat Problem – Types of Thermostats

First, we need to distinguish between the different types of thermostats available on the market. There are thermostats that are battery powered only and need to have fresh batteries replaced from time to time. It is a possibility that your thermostat is this type of thermostat. Possibly, also why your display is not working. You will notice the display starting to fade a little when the batteries are getting low. Furthermore, some of the battery powered thermostats have a battery indicator on the display and some do not.

The thermostats with the battery indicator on the display will tell you when your batteries are low. They also give you an indication when the batteries need to be replaced. Other types of thermostats will not tell you when to replace the batteries. Those without the indicator will cause you to guess when to replace the batteries. Furthermore, if you have either of these thermostats and your display is not working then the first thing you need to do is try to replace the batteries.

Blank Display on Thermostat Problem - Power

The other types of thermostats use the 24 volts from the transformer that is inside your HVAC equipment for power. These thermostats use power stealing technology for their primary source of power. Consequently, a problem with the low voltage part of your HVAC equipment can fail for various reasons. Therefore, this will cause your thermostat display not to work. There are thermostats that use both batteries as a backup power source. Additionally, they also use the 24-volt system from the HVAC equipment. As the primary source of power, it is possible to have a display on your thermostat but have a problem with the 24-volt system. This will likely result in a service call from an HVAC contractor. Furthermore, they have the skills to figure out why the thermostat is not responding or is blank at the display.

Blank Display on Thermostat Problem - Modern Thermostats

Most of the modern thermostats today use the power stealing technology. These thermostats utilize the low voltage system (24-volts) of the transformer located in your HVAC equipment. If you have problems with the 24-volt low voltage system calling an HVAC contractor is best. The contractor can troubleshoot the problem quickly and efficiently. There are many things including safety related things than can cause you to loose the 24 volts. Furthermore, these issues result in no or a blank display on the thermostat.

For example, a high limit switch on a gas furnace can trip for safety related reasons. Professional HVAC contractors can troubleshoot the problem and fix it properly so there is not a safety related issue. It could be something very serious or it could simply be a bad switch. The HVAC contractor will be able to tell what the exact problem is and repair it quickly and efficiently. You can be assured there will be no further problems with the HVAC equipment or the display.

Power Check | Blank Display on Thermostat Problem - Screen Disappeared

The possible reason your thermostat screen can go blank is a loss of power to the furnace. Power stealing thermostats get their power from the transformer. Most modern thermostats are powered by the transformer in your air handler or furnace. In rare case the transformer could be located in the condensing unit. It depends on what type of HVAC system you have. Either way, the power comes from the transformer. If there is no power to the transformer then the thermostat screen will be blank. First, check the breaker to make sure it has not tripped. Air conditioner breakers trip for various reasons. Additionally furnace breakers trip also for various reasons that may not be related at all to your thermostat. Furthermore, if you reset the breaker and it trips again you have a serious problem and need to consult an HVAC contractor.

Other possible reasons why your thermostat screen is blank or dead is the transformer is bad or a thermostat wire is not connected or broken. I’ve seen cases where a squirrel got into the attic and chewed on the thermostat wire and caused a transformer or transformer fuse to go bad. Additionally, if someone has driven a nail in the wall and nicked the thermostat wire inside the wall. Additionally, that could cause problems with your thermostat including causing the screen to go blank.

Conclusion | Blank Display on Thermostat Problem - Screen Disappeared

In conclusion, check the following:

  • Check the thermostat for bad batteries if your thermostat is equipped with batteries
  • Check the breaker for the air handler and condensing unit. Additionally, any power switch that may be near the air handler and control the power for the air handler or furnace.
  • Inspect any visible wiring including the wiring attached to the thermostat and at the air handler or furnace.

If any of these things are beyond your skill level or you do not feel comfortable doing them please consult a professional. Thanks and good luck!!

High Performance HVAC

Blank Display on Thermostat Problem

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