Unlock Your MRCOOL Thermostat: A Comprehensive Guide

Unlocking your MRCOOL thermostat can be a straightforward process, but it’s essential to follow the right steps to ensure a successful outcome. This comprehensive guide will walk you through the necessary steps to unlock your MRCOOL thermostat, from reading the manual to performing firmware updates, providing you with the technical expertise and hands-on guidance to get the job done.

Read the Manual Thoroughly

Before attempting to unlock your MRCOOL thermostat, it’s crucial to read the manual thoroughly. The manual provides detailed information about the thermostat’s features, specifications, and troubleshooting procedures. Pay close attention to the sections on thermostat operation, programming, and unlocking, as they will be essential in guiding you through the process.

Verify the Thermostat Ratings

how to unlock a MRCOOL thermostatImage source: nan

Ensure that the MRCOOL thermostat is suitable for your application by checking the ratings provided in the instructions. The thermostat’s temperature setting range for heating should be between 40°F to 90°F (4°C to 32°C), and for cooling, it should be between 50°F to 99°F (10°C to 37°C). Verify that these ranges match your specific heating and cooling requirements.

Proper Installation by a Trained Technician

The MRCOOL thermostat should be installed by a trained, experienced service technician. Improper installation can lead to various issues, including the inability to unlock the thermostat. After the installation is complete, use the instructions to thoroughly check the product’s operation and ensure it’s functioning as intended.

Navigating the Screen Locks

In the User or Installer Setup menu, you’ll find option 0670, which allows you to prevent changes to all of the touchscreen functions. When this feature is enabled, all keys on the thermostat will be locked, and the screen will display a continuous lock icon. To unlock the keys and restore the touchscreen functions, you’ll need to navigate to the User Setup menu and make the necessary adjustments.

Recalibrating the Remote or Unit

If you’re experiencing issues with the Follow Me feature, where the units maintain the room temperature at 67°F, with a difference of 7°F from the set temperature of 74°F, you may need to recalibrate the remote or the unit. Refer to the manual or contact the manufacturer for specific instructions on how to perform this recalibration process.

Setting Up the WiFi Thermostat

To set up your MRCOOL Universal WiFi Thermostat, follow the instructions provided in the manual or watch the setup video on the manufacturer’s YouTube channel. This process will ensure that your thermostat is properly connected to your home’s WiFi network and can be controlled remotely using the MRCOOL app.

Performing Firmware Updates

If you encounter any issues with the MRCOOL App Mini-Stat, you can perform a firmware update by following the instructions provided in the video on the manufacturer’s YouTube channel. Keeping your thermostat’s firmware up-to-date can help resolve any software-related problems and ensure optimal performance.

By following these steps, you’ll be well on your way to unlocking your MRCOOL thermostat and ensuring its proper operation. Remember to always refer to the manufacturer’s instructions and seek the assistance of a trained technician if you encounter any difficulties or have concerns about the safety of the process.


  1. Reddit Discussion on Unlocking MRCOOL Thermostat
  2. Garage Journal Forum Thread on MRCOOL Thermostat Issues
  3. MRCOOL MST03 Installation Manual
  4. MRCOOL Universal WiFi Thermostat Setup Video
  5. MRCOOL App Mini-Stat Firmware Update Video