Troubleshooting Heat Pump Thermostat Not Turning On: A Comprehensive Guide

The heat pump thermostat is responsible for controlling the heat pump’s heating or cooling cycles based on sensor readings. If the thermostat is not turning on, the heat pump will not receive the signal to start, resulting in the heat pump not functioning. This comprehensive guide will provide you with a step-by-step approach to troubleshoot and resolve the issue of a heat pump thermostat not turning on.

Checking the Thermostat Settings

The first step in troubleshooting a heat pump thermostat that is not turning on is to check the thermostat settings. Ensure that the thermostat is set to the correct mode (heating or cooling) and that the temperature setting is appropriate for the desired temperature. Check the thermostat display to see if it is showing any error messages or if the backlight is illuminated, indicating that the thermostat is receiving power.

If the thermostat settings appear to be correct, you can try the following steps:

  1. Clean the Thermostat: Use a soft, dry cloth to gently wipe the thermostat’s surface and remove any dust or debris that may have accumulated. Avoid using any liquids or cleaning agents, as they can damage the internal components.

  2. Check the Thermostat Wiring: Ensure that the thermostat is properly connected to the heat pump’s control board. Inspect the wiring for any signs of damage, such as fraying or loose connections. If necessary, tighten the wire connections or replace any damaged wires.

  3. Verify the Thermostat’s Power Source: Depending on the thermostat model, it may be powered by batteries or directly from the heat pump’s control board. Check the thermostat’s power source and replace the batteries if necessary. If the thermostat is wired directly to the control board, ensure that the power supply to the control board is functioning correctly.

Checking the Thermostat Batteries

If the thermostat is battery-powered, the next step is to check the battery condition. Low or dead batteries can prevent the thermostat from turning on. Follow these steps to check and replace the batteries:

  1. Locate the Battery Compartment: Typically, the battery compartment is located on the back or bottom of the thermostat. Gently remove the thermostat from the wall to access the battery compartment.

  2. Inspect the Batteries: Examine the batteries for any signs of corrosion or leakage. If the batteries appear to be in good condition, try replacing them with fresh, high-quality batteries.

  3. Reinstall the Thermostat: Once you have replaced the batteries, carefully reinstall the thermostat on the wall, ensuring that it is securely mounted and the wiring is properly connected.

  4. Test the Thermostat: After replacing the batteries, turn the thermostat on and check if it is now functioning correctly. If the thermostat still does not turn on, proceed to the next troubleshooting step.

Addressing Proximity to Heat Sources

The thermostat’s sensor readings can be affected by the proximity of heat sources, such as space heaters, direct sunlight, or drafty windows. If the thermostat is located near these heat sources, it may receive inaccurate temperature readings, causing it to malfunction.

To address this issue, follow these steps:

  1. Identify Heat Sources: Carefully inspect the area around the thermostat and identify any potential heat sources that may be affecting the sensor readings.

  2. Relocate the Thermostat: If possible, relocate the thermostat to a more suitable location, away from any heat sources. Ensure that the new location is not affected by drafts or direct sunlight.

  3. Adjust the Thermostat Settings: After relocating the thermostat, you may need to adjust the temperature settings to ensure accurate readings and proper operation of the heat pump.

Checking the Heat Pump Power Connection

In some cases, the heat pump power connection may be faulty, preventing the thermostat from turning on. Follow these steps to check the power connection:

  1. Locate the Circuit Breaker: Identify the circuit breaker that supplies power to the heat pump and ensure that it is in the “ON” position.

  2. Check for Tripped Breakers: If the circuit breaker has tripped, reset it. If the breaker continues to trip, there may be an electrical fault in the heat pump that requires professional attention.

  3. Inspect the Wiring: Visually inspect the wiring between the heat pump and the thermostat for any signs of damage, such as fraying or loose connections. Tighten any loose connections and replace any damaged wires.

  4. Test the Power Supply: Use a multimeter to check the voltage at the thermostat’s power terminals. Ensure that the voltage is within the recommended range for the thermostat.

If the power connection appears to be functioning correctly, but the thermostat still does not turn on, it may be necessary to call a professional HVAC technician to diagnose and repair the issue.

Seeking Professional Assistance

If you have followed all the troubleshooting steps and the heat pump thermostat is still not turning on, it is recommended to call a professional HVAC technician. They have the expertise and specialized tools to diagnose and repair more complex issues that may be beyond the scope of a DIY approach.

Some common reasons why a professional technician may be required include:

  • Faulty thermostat control board or internal components
  • Issues with the heat pump’s compressor or other internal components
  • Electrical problems that require advanced troubleshooting and repair
  • Compatibility issues between the thermostat and the heat pump

By calling a professional HVAC technician, you can ensure that the issue is properly diagnosed and resolved, restoring the proper functioning of your heat pump system.


Troubleshooting a heat pump thermostat that is not turning on can be a complex process, but by following the steps outlined in this comprehensive guide, you can effectively identify and address the underlying issue. Remember to always prioritize safety and consider seeking professional assistance if the problem persists or if you are unsure about the appropriate course of action.