Thermostat Not Working in Las Vegas: Blank Screen, Wrong Mode, and What to Try Once

A lot of “AC dead” and “heater dead” calls in the Las Vegas Valley start at the thermostat. The equipment is fine. The display is blank, the mode is wrong, the batteries are dead, or a schedule is holding an old setpoint.

This page is the thermostat pass. If the thermostat is calling correctly and the system still fails, move to the equipment guides: AC running but not cooling, heater not working, furnace short cycling.

Colton Air Conditioning schedules these calls Monday–Friday, 8am–5pm.

Checks you can do once

1. Mode and setpoint

Confirm the mode matches what you want: Cool in summer, Heat when you need heat, not Off or Fan-only unless you meant that. Set the temperature a few degrees past the room temperature on the display.

Fan should usually be Auto. Fan On runs the blower without asking the system to cool or heat.

2. Blank or dim screen

A blank screen is often dead batteries on a battery-powered thermostat. Replace them, then recheck mode and setpoint.

If the thermostat is powered from the furnace or air handler (common on many digital and smart stats), a blank screen can mean the equipment lost power — furnace switch off, tripped breaker, or a blown low-voltage fuse. Check the furnace/air handler switch (looks like a light switch) and reset the HVAC breaker once. If the breaker trips again, leave it off.

3. Schedule and hold

A schedule can wake up at an old setpoint and make a working system look dead. Look for Hold, Schedule, or Vacation on the display. Set a temporary hold a few degrees past the room temp and wait a few minutes for a call for cool or heat.

4. Smart thermostat Wi‑Fi

Wi‑Fi down does not always stop local Heat/Cool buttons. If the app is offline, use the buttons on the wall. If the wall display is blank and batteries/power checks failed, stop. Do not keep pairing and resetting overnight.

5. Heat pump extras

If you have a heat pump, leave it on Heat for normal mild-valley nights. Do not park it on Emergency Heat to “fix” a blank screen. Emergency heat is backup strip heat, not the everyday setting.

What those checks usually mean

A thermostat that clicks and the outdoor unit never starts can still be a capacitor, contactor, or control issue at the equipment — not a new thermostat from the hallway. Same for a furnace that never lights after a good Heat call.

What not to do

• Do not replace the thermostat as the first move on a no-cool afternoon.
• Do not keep flipping breakers if one reset already failed.
• Do not rewire a smart thermostat yourself if you are unsure which wire is which.
• Do not ignore a burning smell at the thermostat or the air handler — shut the system down.

Related: AC tripping the breaker, AC repair Las Vegas.

When to call

Call when the display stays blank after batteries and one power check, the thermostat calls and nothing happens at the equipment, the breaker will not stay on, or you smell burning at the stat or cabinet.

Have ready if you can: brand of thermostat if shown, battery or hardwired if you know, Cool or Heat season, and the symptom in plain words (“blank screen,” “app works / wall blank,” “set to Cool, outdoor unit silent”).

Hours are Monday–Friday, 8am–5pm. If the house is uncomfortable outside those hours, finish the checks above and call when we are open.

FAQ

Blank screen — always batteries?

Often on battery stats. On powered stats it can be a furnace switch, breaker, or low-voltage fuse. One power check, then stop.

Can a bad thermostat make the AC run but not cool?

Sometimes it can call wrong, but warm air with the outdoor unit running is often airflow, charge, or compressor — see AC running but not cooling.

Should I upgrade to a smart thermostat while you are there?

Only after the system is diagnosed. A new thermostat does not fix a failed capacitor or a clogged drain.

What hours can I reach Colton?

Monday through Friday, 8am to 5pm.

Still blank or still no call after the checks above? Call Colton Air Conditioning at (702) 738-6976 Monday–Friday, 8am–5pm. Tell us what the display shows and what you already tried. We will tell you if we can see it.

Colton Air Conditioning · Las Vegas Valley residential HVAC · Monday–Friday 8am–5pm

Call (702) 738-6976 or Book Online. License 0092120. Hours Monday through Friday, 8am to 5pm. Saturday and Sunday are closed.

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