Heat Pump Outside Home

Heat Pump Stuck in Heat Mode? How to Fix It

Heat pumps are a great solution for maintaining comfortable temperatures in your home year-round. They provide both heating and cooling by transferring heat between the indoor and outdoor environments. However, like any complex system, they can occasionally encounter issues. One common problem is when the heat pump gets stuck in heat mode. This blog will guide you through understanding why this happens and how to fix it.

Understanding the Problem: Heat Pump Stuck in Heat Mode

When your heat pump is stuck in heat mode, it fails to switch to cooling, leaving your home uncomfortably warm. This issue can stem from several causes, including problems with the thermostat, the reversing valve, or the control board.

1. Thermostat Issues

The thermostat is the brain of your HVAC system. If it’s malfunctioning, it may not properly signal the heat pump to switch modes. Ensure your thermostat is set correctly and functioning. Sometimes, a simple reset or replacing the batteries can resolve the issue.

2. Reversing Valve Problems

The reversing valve is a critical component that allows the heat pump to switch between heating and cooling. If it gets stuck or malfunctions, the heat pump may remain in heat mode. Diagnosing and fixing reversing valve issues can be complex and often requires professional help.

3. Control Board Malfunctions

The control board manages the overall operation of the heat pump. If it’s faulty, it might not send the right signals to switch from heating to cooling. This issue typically needs a professional HVAC technician to diagnose and repair.

Troubleshooting Steps: How to Fix a Heat Pump Stuck in Heat Mode

Now, let’s walk through some troubleshooting steps to help you fix your heat pump stuck in heat mode.

Step 1: Check the Thermostat

Start with the simplest solution by checking your thermostat settings. Ensure it’s set to “cool” mode and the temperature is lower than the current room temperature. If the thermostat uses batteries, replace them to see if that resolves the issue. If you have a programmable thermostat, check the schedule settings to make sure it’s not overriding your desired temperature.

Step 2: Inspect the Reversing Valve

If the thermostat seems fine, the next step is to inspect the reversing valve. This component switches the heat pump from heating to cooling. If the valve is stuck, it may need manual assistance to shift back. However, this step can be tricky and requires some technical knowledge. If you’re not comfortable doing this yourself, it’s best to contact a professional.

Step 3: Test the Control Board

If the reversing valve isn’t the problem, the control board might be the culprit. The control board oversees the heat pump’s functions, and if it’s not working correctly, the heat pump won’t switch modes. Testing and replacing the control board is typically a job for a professional HVAC technician, as it involves working with electrical components.

Step 4: Check for Refrigerant Leaks

Low refrigerant levels can also cause your heat pump to get stuck in heat mode. If the system is low on refrigerant, it may not have enough pressure to switch the reversing valve. Checking and refilling refrigerant is not a DIY task and should be handled by a certified HVAC technician.

How to Unstick a Reversing Valve on a Heat Pump

One of the more common reasons for a heat pump stuck in heat mode is a stuck reversing valve. Here’s a step-by-step guide on how to address this issue:

Step 1: Turn Off the Power

Before doing anything, ensure the power to the heat pump is turned off to avoid any electrical hazards.

Step 2: Locate the Reversing Valve

The reversing valve is typically found near the compressor. Consult your heat pump’s manual for the exact location if you’re unsure.

Step 3: Manual Adjustment

Sometimes, gently tapping the reversing valve with a rubber mallet can unstick it. Be very cautious with this step to avoid causing any damage. If you’re not confident, skip this step and contact a professional.

Step 4: Professional Help

If the manual adjustment doesn’t work, it’s time to call a professional. HVAC technicians have the tools and expertise to safely and effectively unstick or replace a malfunctioning reversing valve.

What If the Heat Pump Won’t Come On?

In some cases, the heat pump might not come on at all, indicating a more severe issue. Here are some potential causes and solutions:

1. Power Supply Issues

Ensure that the heat pump is receiving power. Check the circuit breakers and any fuses associated with the heat pump.

2. Thermostat Malfunctions

As mentioned earlier, the thermostat plays a crucial role. If it’s not working, the heat pump won’t receive the signal to turn on. Try resetting or replacing the thermostat.

3. Internal Component Failures

Failures in components like the compressor, capacitor, or control board can prevent the heat pump from operating. These issues usually require professional diagnosis and repair.


A heat pump stuck in heat mode can be a frustrating issue, especially during the warmer months. By following the troubleshooting steps outlined in this guide, you can identify and possibly fix the problem. However, some issues, particularly with the reversing valve and control board, are best handled by professionals.

If your heat pump is stuck in heat mode, or if it won’t come on at all, don’t hesitate to reach out to Ultimate Heating & Air. Our team of experienced HVAC technicians is here to help with all your heating, cooling, and plumbing needs. Contact us today to schedule a service appointment and ensure your home remains comfortable year-round.


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