Why Ecobee Thermostat Not Turning On AC? – Troubleshooting Guide

The Ecobee thermostat is a smart device that allows you to control your home’s temperature remotely. The device is also equipped with sensors that allow it to “learn” your heating or cooling needs and adjust accordingly. If your Ecobee thermostat won’t turn on the AC, there are a few possible causes for it.

Your Ecobee thermostat will not turn on your AC if it has not been set to turn it on or you have a clogged AC drain line. Other reasons could be an overfilled drain pan, a blown fuse or tripped circuit breaker, or a faulty air conditioning system.

Sometimes your Ecobee thermostat will turn on the AC but then shuts off after a few minutes, or it doesn’t turn on. Read on to find out why your smart Ecobee thermostat is not turning on the AC and how to fix it.

1. Overfilled Drain Pan

A drain pan is meant to catch condensate and other liquids in an HVAC system. The pan collects the water and drains it outside. Draining is essential because if this water goes into your basement, it can cause mold and mildew to grow.

When the Ecobee thermostat detects the drain pan is overfilled, it will not turn on the AC to prevent damage to the HVAC system. 

An overfilled HVAC drain pan can cause severe damage to your home. Excess moisture can cause problems such as excess humidity, allergies, and structural issues. If you notice that your drain is overflowing, you should take action as soon as possible. 

How To Fix?

If you believe your Ecobee thermostat isn’t turning on the AC due to an overfilled drain pan, here are some quick fixes:

  1. Turn off your AC and remove the drain cover to empty excess water in a sink or bucket.
  2. Check if there’s too much sediment, mold, or algae in your condensate drain pan, and clean it.
  3. Check the pan periodically so that it doesn’t overflow again.

Read: 4 Reasons Why Ecobee Thermostat Fan Keeps Running

2. Clogged AC Drain Line

Your AC drain line is the pipe that leads from your air conditioner to the outside of your home. You should clean the drain line regularly to prevent clogging. 

The signs of a clogged HVAC drain line causing the Ecobee thermostat not to turn on AC are the following:

  • The AC unit is not turning on.
  • The system is blowing hot air.
  • There is no cool air coming out of the vents.
  • There is a lot of condensation in the room.
  • Loud noise can be heard when you try to turn on the AC unit.
  • The fan doesn’t turn on.
  • The unit may turn off after a few minutes of running.

When the AC drain line is clogged, it prevents water from flowing through, and this may trigger your Ecobee thermostat to shut off your AC automatically. 

How To Fix?

To fix this issue, you should first try using a plunger or vacuum to remove any debris that may be blocking the flow of water, and then use a drain snake or auger to clear out any remaining blockage. Make sure the drain line is completely clear before turning on the AC again.

Read: 3 Reasons Why Ecobee Thermostat Is Overheating

3. Blown Fuse or Faulty Circuit Breaker

When your Ecobee thermostat doesn’t turn on your AC, there are three possible causes: 

  • a blown fuse 
  • a faulty circuit breaker
  • an issue with the thermostat itself 

How To Fix?

The first step is to check if there’s power in your home using an outlet tester. 

I suggest using the Klein Tools RT250 GFCI Receptacle Tester with LCD Display (available on Amazon.com). It works for standard 120V North American outlets and flashes specific colors to indicate what issue you’re experiencing. With a safety rating of CAT II 135V, it should work for regular home appliances and power outlets.

If there’s power in all of the outlets in your home, check the fuse and circuit breaker. The Ecobee thermostat has a built-in circuit breaker to turn AC on and off. When the circuit breaker trips, it will stop the compressor from turning on.

When you have a blown fuse or faulty circuit breaker, there are a couple of things that you can do to get your Ecobee thermostat back up and running:

  • Unplug the power cord from the wall outlet and inspect the fuse or circuit breaker. You can get assistance from a qualified technician to help you replace your fuse or circuit breaker.
  • Reset your thermostat by unplugging it from its power source for 10 seconds, then plug it back in again.

Read: No Power To The Home Temperature Thermostat – Troubleshooting Guide

4. Ecobee Thermostat Has Not Been Set To Turn On AC

You can automatically program the Ecobee thermostat to adjust the temperature according to your need. The Ecobee thermostat can “remember” when you’re home and when you’re away so it can automatically turn off the AC when you’re not around and turn it on once you get back home.

However, sometimes this feature doesn’t work as intended or at all, which can be caused by the wrong temperature settings. For instance, if you set the thermostat to turn on the AC at 70 degrees, it won’t turn on until the temperature in your room reaches 70 degrees.

Air conditioners have a minimum compressor cycle-off time when the compressor shuts down for a specific duration of a set time. Your Ecobee thermostat will not turn on the AC during this time.

How To Fix?

Keep in mind that the Ecobee thermostat will control your home’s HVAC system based on preset commands.

If your Ecobee thermostat isn’t automatically turning on the AC, you may be able to fix it by following these steps:

  1. Launch the Ecobee app.
  2. Tap the three horizontal lines in the upper-left corner of the screen. 
  3. Select “Set Thermostat” from the menu that appears.
  4. Select “Change Settings” at the top of this menu.
  5. Scroll down to “AC Setting” and adjust your preferred temperature settings.

I recommend contacting Ecobee support or an appliance technician for further assistance if none of the above steps work.

Read: How To Fix Ecobee Alexa Not Responding?

5. Faulty Air Conditioning System

If you notice that your Ecobee thermostat isn’t turning on your air conditioning, it could be a sign that the system is faulty.

The Ecobee thermostat has built-in Wi-Fi capabilities to help you remotely control your HVAC system. It uses sensors that recognize when your HVAC is broken or there’s no power running and automatically turn off your heating or cooling system.

If you notice any of these signs, it’s time to call in a professional to fix the issue:

  • The temperature in the room fluctuates significantly throughout the day.
  • The unit is noisy.
  • You hear strange sounds coming from the unit.
  • The thermostat won’t turn on the AC even though it’s set at the desired temperature.

How To Fix?

The Ecobee thermostat will automatically turn off your AC when it detects a fault in the air conditioning system. In this case, you will need to fix the faulty HVAC system. 

When your HVAC system is not working, you must take some steps. 

  1. Check the thermostat and ensure it’s appropriately set up. 
  2. Check for any faults in your air conditioning system and repair them if necessary. 

It would be best to call an appliance technician to fix the faulty HVAC system and ensure your Ecobee thermostat will work properly again.

Read: Why Is House Thermostat Reading The Wrong Temperature?

Final Thoughts

The Ecobee thermostat is a popular smart thermostat you can control remotely via smartphone or tablet. You set the temperature, and the thermostat will adjust it automatically based on the time of day and your preferences.

The device can also help you conserve energy by learning your habits, adjusting the temperature accordingly, and even creating a schedule for your home so that you don’t have to worry about manually adjusting the thermostat throughout the day. 

It’s crucial to perform regular maintenance on your system to avoid frustrations when your Ecobee doesn’t turn on the AC.