Sensi Thermostat Not Working: Heat, Cool and Wi-Fi Fixes

By Ray Bennett · Updated 2 October 2026 · 6 min read · Checked against the maker’s manual

Sensi Thermostat Not Working: Heat, Cool and Wi-Fi Fixes

Short answer

Sensi's own test is to switch the mode off, then to heat or cool with the set point a few degrees past the room, and listen for a click. No click means the thermostat, so check the batteries and reset it. A click and no air means the furnace or air conditioner. A heat pump that cools in Heat mode needs its reversing valve setting changed from o to b.

A Sensi thermostat that will not heat or cool is either the thermostat not asking, or the equipment not answering. Sensi’s own help pages give a simple test that tells you which, and a short list of settings that catch people out after an install.

Everything on this page comes from Sensi’s support articles. Sensi is now a Copeland brand, and it covers the Sensi smart thermostat, the Sensi Lite, and the touchscreen Sensi Touch and Touch 2.

Before you start

What to carry: a torch, fresh batteries, and a multimeter if you want to check the voltage. Fifteen minutes.

Gas or electric? Either. Sensi says its thermostats work with the heating and cooling in most homes, heat pumps included. What matters is that it is set up for yours.

Which Sensi? The Sensi smart thermostat takes 2 AA alkaline batteries and the Sensi Lite takes 2 AAA. The Touch and Touch 2 have no batteries and need a common wire.

Before you touch the wires. Power off. Switch the heating and cooling off at the breaker before taking the thermostat off the wall or moving any wire.

Resets are a tool, not a first step. Sensi recommends resetting only when its support instructions say to. After a reset you must reconnect the thermostat to Wi-Fi, and Sensi says to allow 30 to 60 minutes for it to recalibrate the room temperature.

Sensi’s click test

Sensi's test in three steps. A click with no warm or cool air points past the thermostat, at the equipment.

Check 1Free, five minutes

Run the test

Mode off first. The app background turns gray, and so does the Touch screen. On the Touch 2 the room temperature number stops being orange or blue, and on the Lite the word ON disappears.

Then heat or cool. Switch to Heat and set the temperature a few degrees above the room, or to Cool and a few degrees below it.

Listen for the click. On the Sensi smart and the Lite, a click means the thermostat is turning your system on. The Touch, the Touch 2 and the app turn orange for heat and blue for cool, and you still hear the click.

Give it a moment. Sensi says a gas or boiler system may take a few minutes to start.

No click. Sensi says to reset the thermostat and try again. The resets by model are further down.

A click, but no warm or cool air

Check 2Free, fifteen minutes

Check the equipment

Batteries. On the Sensi smart and the Lite, Sensi says low batteries may stop it turning on the system.

The power switch. Sensi says most systems have a switch like a light switch on or near the furnace or air handler. Make sure it is on, then turn the breaker off and on again at the panel.

After a power surge. Sensi says to wait a few minutes after your other electronics come back on, then reset the thermostat and test again.

The furnace door. Sensi says a loose blower door can keep the equipment from running, because it has to press a safety switch.

A blinking light inside. Sensi points out that the code is unique to each maker: what a furnace’s blinking light means by brand.

The filter and the drain. Sensi names a clogged filter or a clogged condensate drain as things that can stop the system.

A heat pump blowing the wrong air

Sensi's reversing valve setting. If a heat pump cools in Heat mode and heats in Cool mode, it needs b instead of o.

Check 3Free, ten minutes

Fix the setup

Cooling in Heat, heating in Cool. Sensi’s answer is the reversing valve setting. The default is o. If your heat pump does the opposite of what you ask, change it to b.

Cannot switch to Heat or Cool. Sensi says the configuration may have been changed by accident. The outdoor setting should be HP1 for a heat pump or AC1 for an air conditioner, or HP2 and AC2 for two stages with a wire in Y2.

Two sets of labels. If your old thermostat had two sets of terminal labels, Sensi says to be sure you picked the ones for your system type in the app.

Redo it in the app. Sensi’s route is the plus sign, your Sensi, New Installation and Is Currently Mounted, then follow the steps: what each thermostat wire does.

The 20 volt check

Check 4Free, ten minutes

Measure the thermostat's power

How. Set a meter to AC volts. Measure from RH or RC to G, then from RH or RC to Y for cooling, or to W or E for heating.

What Sensi wants. Sensi says with less than 20 volts AC, the thermostat will not be able to turn on your system.

The swap test. If you still have your old thermostat, Sensi suggests putting it back. If the old one works, the Sensi is the problem; if not, the system is.

Resetting it, by model

Model	Sensi’s reset
Sensi smart thermostat	Hold the up arrow, down arrow and Fan buttons together until the display flashes and reboots
Sensi Lite	Hold the up arrow, down arrow and menu buttons together for over a second until the display resets
Sensi Touch	Menu, then About thermostat, then Factory Reset
Sensi Touch 2	The menu icon, then About thermostat, then Factory Reset

An X on the screen: Wi-Fi

Check 5Free, twenty minutes

Get it back online

What the X means. Sensi says an X, or Not connected to network, means the thermostat cannot reach your Wi-Fi.

A new router or password. Reconnect the thermostat to the new network.

Reboot the router. Sensi says unplug it for 5 to 10 minutes, then allow 1 to 5 minutes for it to reconnect.

The 2.4 GHz network. Sensi says 2.4 GHz networks have greater range, and suggests trying it on a model that can also use 5 GHz.

The hotspot test. Sensi’s test is connecting the thermostat to a phone’s hotspot. If that works, the problem is a setting or compatibility issue with your router.

Questions people ask

Why is my Sensi blowing hot air on cool?

On a heat pump, the reversing valve setting is probably wrong. Sensi’s default is o; if the system heats in Cool mode and cools in Heat mode, change it to b.

Why is my Sensi not turning on the heat?

Run Sensi’s click test. No click points at the thermostat: batteries, settings or a reset. A click with no heat points at the furnace: its switch, breaker, door or a blinking code.

How do I reset my Sensi thermostat?

On the Sensi smart, hold up, down and Fan together until it reboots. On the Lite, hold up, down and menu for over a second. You will need to reconnect Wi-Fi afterwards.

What batteries does a Sensi take?

The Sensi smart thermostat takes 2 AA alkaline batteries and the Sensi Lite 2 AAA. The Touch and Touch 2 have none and need a common wire.

Does a Sensi need a C wire?

The Touch and Touch 2 do. The Sensi smart and Lite run on batteries, though Sensi says heat only, cool only, heat pump and zone systems do require a common wire.

Why does my Sensi show an X?

It is not connected to Wi-Fi. Reboot the router, check the network name and password, and put the Sensi on the 2.4 GHz network.

Sources: Sensi (Copeland) support articles: why isn't my heating or cooling turning on, how do I configure my thermostat, reset Sensi, replacing batteries, what is a common wire, and not connected to Wi-Fi