Why Is Vivint Thermostat Not Turning On AC? Complete Fix!

If your Vivint thermostat not turning on AC, there are several quick fixes!

The Vivint thermostat has to automatically enable your AC, upon setting a heating/cooling or an AUTO mode through the device’s interface.

However, there could be an issue that’s preventing you from doing that and we will get it all reviewed in this post!

If Vivint isn’t turning on the AC in the HVAC system, the problem could be with the device’s batteries. The power supply to the AC might have been cut or the safety switch on the furnace pipe has been spun.

Let’s review in proper detail what could be causing the problem with your Vivint thermostat.

Why Is The Vivint AC Thermostat Not Turning On?

There could be multiple reasons why your Vivint thermostat is unable to boot the AC.

There isn’t anything hidden in this issue, except for the fact that your thermostat could have gone faulty, which we will exclude for now.

Besides a hardware failure, here is what might have happened to your thermostat:

1. Worn-Out Batteries

One of the main causes for your not working Vivint thermostat is worn-out batteries within the device, thus it won’t control the AC’s functionality.

2. Flipped Safety Switch

If you’ve enabled the safety switch’s functionality in your HVAC system pipe, the thermostat won’t turn on the AC.

3. AC is Disconnected

Not having your AC connected to the power will result in your Vivint thermostat being unable to start up.

4. The Circuit Breaker Is Flipped

You could have accidentally disabled the power supply to the entire room.

5. AC Drain Line Is Full

The drain pipe of your AC might have gotten clogged and so the AC will refuse to turn on regardless of whether you’re turning it on manually or through the thermostat.

This is everything you need to know about the issue’s causes. To solve the problem, check the solutions further down in our guide.

How To Fix Vivint Thermostat Not Turning On AC?

After quickly reading about the issue’s main causes, it’s time to solve the issue with our approved solutions.

Follow the exact order of our troubleshooting solutions so you can get the best effects at fixing the problem.

Here’s how to fix a Vivint thermostat when it won’t turn on the AC:

Solution #1 Power Cycle Thermostat

You should begin the guide with a power cycle of your Vivint thermostat.

That will clear out any temporal bugs or glitches that are preventing you from turning on the AC.

The power cycle involves taking the batteries out and then reinserting them.

Here’s how to power cycle your Vivint thermostat:

1. Go next to your Vivint thermostat unit.
2. Take the front panel apart from the base.
3. Expose the 4 battery units inside.
4. Take all of the batteries out.
5. Standby for 5 minutes until the thermostat gets discharged completely.
6. Reinsert the batteries.
7. Test.

Note: Ensure that you’re placing the batteries inside of your thermostat correctly so the thermostat is capable of starting up.

Solution #2 Reset The A/C

Chances are that your AC isn’t connected to the power or doesn’t receive electricity through it in the first place.

If that’s the case regardless of what you attempt to do through the thermostat, it won’t turn on the AC.

Here’s how to reset your A/C in easy-to-follow steps:

1. Go over to the AC’s power supply.
2. Locate the power source that the device is connected to.
3. Unplug the power adapter of the AC.
4. Standby for 5 minutes with the device’s adapter being disconnected.
5. Re-attach the supply of the AC into the respective slot.
6. Test your AC.

Note: Make sure to avoid any power strips or dividers for connecting your AC to the power.

Solution #3 Flip The Safety Switch

In your HVAC system’s compartment, locate the pipe coming out of your furnace.

On this exact pipe, there should be somewhere a Safe-T switch that enables and disables the system’s heating and cooling function.

This switch should be located somewhere in the middle of the pipe and requires a slight force to be turned.

Force is required due to the anti-child protection. The switch has a little plus and minus labeled on it and should be put to the negative side.

Note: When spun to the negative, the safety switch will no longer block the functionality of your furnace and thermostat.

Solution #4 Replace Thermostat Batteries

If your thermostat doesn’t seem to be triggering the AC, the device has most likely run out of batteries.

If that’s the case, by replacing the batteries you should finally fix the connection with your AC.

Check out the instructions to change the batteries of your Vivint thermostat:

1. Open the front compartment of the thermostat.
2. Eject all of the batteries.
3. Insert new batteries inside your thermostat.
4. Re-attach the panel and test.

Note: Mind the polarity of the electric poles and the way you insert the batteries into your thermostat.

Solution #5 Clean AC Drain Line

As you probably know, every AC in an HVAC system has a drain line. If that drain line gets clogged, the AC will automatically be prevented from functionating to avoid breaking the drain line.

It’s a safety mechanism and to solve the problem you would need to thoroughly clean the drain line.

Here’s how to clean your AC’s drain line:

1. Disconnect your AC from the power.
2. Grab a long stick and go to the drain line.
3. Push all garbage and dirt downwards of the drain line.
4. Pour some water into the drain line to soften the trash up.
5. Collect the remaining dirt using a vacuum.

Note: Ensure that your drain line has fully dried up before plugging the AC into the power source and resuming its work.

Solution #6 Reset The Vivint Thermostat

In case our solutions weren’t helpful so far, perhaps a factory reset on the thermostat will help fix the AC’s startup.

The reset will erase all software configurations made to your thermostat and restore it to default settings.

Here’s how to reset your Vivint thermostat easily:

1. On your Vivint thermostat’s home screen, press the SIDE button for 3 seconds.
2. Next, choose DOWN and highlight the installer.
3. Choose RESET next and press the SIDE button.
4. Wait for your thermostat to be reset.

Note: It may take an average of 5 minutes for your Vivint thermostat to be completely reset.

Thus, to fix a Vivint thermostat that won’t boot the AC, power cycle the thermostat and replace its batteries. Turn the safety switch towards the OFF side and power cycle the AC. Lastly, clean the AC’s drain line and perform a reset on the thermostat.

Read Next: Vivint Thermostat Not Responding To App? (Fixed)

Bottom Line:

We hope that you were able to find out why the Vivint thermostat not turning on AC and how to fix the issue.

You should always keep in mind that contacting your local HVAC technician will get the issue fixed or the cause revealed in a matter of minutes!

If you’ve managed to solve your problem with the help of our guide, make sure to solve other issues you’re experiencing using other solutions from our technical blog!