Why Is My Thermostat Blank?

It is an “Oh no!” moment when you approach your home’s thermostat and see its screen is blank.

Is it serious? Does it mean your furnace, heat pump, or air conditioning is broken? Not necessarily. In fact, most of the time, it is something minor and can be easily fixed.

Chill Out

Here are some of the most frequent reasons our Lightning Mechanical professionals see a thermostat blank screen here in the Land O’ Lakes area:

Dead batteries.

If your thermostat wall does not have a c-wire, or common wire, your thermostat is most likely not hooked up to your heating, ventilation, and air conditioning (HVAC) system for its power and requires batteries. When your screen is blank, it could indicate you need to replace the batteries.

If this is the case, you typically need AA alkaline or 3-volt lithium batteries, so check what type is currently powering the thermostat and simply replace them. Most thermostats display a low-battery symbol when the juice is running low.

On the other hand, if your thermostat is hardwired to your HVAC system for power, it could be a temporary blank screen if the thermostat is in the middle of recharging. Wait a short time and see if the display returns. If it does not, read on.

Loose wiring or wiring problems.

Sometimes the wires hooked up to your thermostat are responsible for its lack of power. If they originally were not firmly attached or the thermostat is in a high-traffic room, the vibrations from people walking by can actually affect the wires.

Our professionals have also seen wires chewed by rodents damage the wiring. According to Humane Society International, these rodents will continue to cause havoc in your Land O’ Lakes home until you locate their entrance/exit opening and permanently seal it.

Since wiring deals directly with electricity, we recommend calling us to diagnose and repair the issue for you. When it comes to electricity, rely on a professional. It is much better to be safe than sorry.

Tripped circuit breaker or blown fuse.

A quick fix to restore your thermostat’s power is a tripped circuit breaker or blown fuse, depending what you have in your Florida home. Sometimes a surge can cause this issue.

If you check your electrical box and a circuit breaker is tripped, just flip it back. If you have fuses, replace the fuse.

Once this is done, check your thermostat. If you have power again, you are set; but if the breaker trips again or the replacement fuse blows, you may have a more involved HVAC problem. You need to get one of our Lightning Mechanical professionals involved.

Tripped safety switch.

HVAC systems have built-in safety switches to protect you in an unsafe situation. In the event one of your unit’s safety switch is tripped, the transformer supplying voltage to your unit (and possibly your thermostat) will stop power.

If your unit is a furnace, you need to call one of our HVAC experts for a diagnosis and repair. If the unit is your heat pump or air conditioner, check its condensate pan to see if it is full. As a safety precaution, a full pan may trip the safety switch. Give us a call if this is the case.

Open furnace door.

Every once in a while, our team members come across an open furnace door causes a blank thermostat. Some thermostats are more sensitive to this issue than others, but it is worth checking. If your furnace door is not closed tightly, your thermostat may turn off. Simply closing the door securely should restore power in this situation.

Old thermostat.

Though thermostats can last 10 to 20 years, they do wear out. Sometimes it is just time to replace it.

If your thermostat is older, unfortunately this may be the problem. If it is, be sure to have one of our HVAC professionals install the new one—newer models can be complicated. You want to be sure to avoid issues with it in the future.

Call Us With Any Thermostat Concerns

At Lightning Mechanical here in Land O’ Lakes, FL we frequently field phone calls regarding thermostat issues. If your thermostat has a blank display, try the aforementioned ideas to see if you can restore its power. But if they are not solving your problem, or if you are hesitant about attempting these on your own, please call us at 813-492-5575 or request service online. We are happy to help.