Why Is My Thermostat Blank But The Fan Will Turn On?

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Why Is My Thermostat Blank But The Fan Will Turn On?

The most sophisticated air conditioners, furnaces, and heat pumps are pretty much worthless if your thermostat stops working. It’s the boss of the system so-to-speak because it tells the HVAC systems in your Waterford, MI or Oxford, MI home to turn on and off at the right time. Modern digital thermostats are marvelous devices in and of themselves, but when the screen goes blank, it’s a good sign something is wrong. Let’s look at some of the common reasons this can happen.


Thermostats can be installed on the same electrical circuit as other devices/appliances. If the breaker trips power is shut off to the thermostat. Sometimes it’s just a matter of turning the circuit breaker back on, but if it keeps happening you need to seek professional help.


Not all residential thermostats are hard wired into the home’s power supply. Instead, they use batteries that should be changed at least once a year. If your battery-powered thermostat screen goes blank, suspect the batteries first. Replace them to see if that solves the problem.


Modern HVAC systems often include fail-safe systems. If monitors detect a problem or damage, a safety switch will turn off the thermostat. Here are two common examples:

  1. During the air conditioning season water is detected in the overflow pan because the condensate drain system isn’t working correctly.
  2. If a furnace gets too hot a safety switch will shut it down before any damage happens.

No matter why the safety switch was triggered, you should have your system inspected immediately.


Inside a thermostat there are lots of electrical wires connected to one or more circuit boards. A bad connection can cause the display to go blank or interrupt communication between the thermostat and the AC or furnace. Unless you have electrical training, Kotz doesn’t recommend fiddling with any wiring problems yourself.


It’s possible your thermostat failed because it needs to be replaced. The average life expectancy is around 10 years. If yours is up there in age, you may just want to replace it rather than attempt any repairs.


Don’t let a problem thermostat be the boss of your Waterford, MI or Oxford, MI house. If you are having problems or are ready to upgrade to the latest smart thermostat, call Kotz Heating, Cooling and Plumbing now to make an appointment. Be sure to like and follow us on Facebook and Twitter for more great HVAC information like this.