Skip navigation


24-Hour Emergency Service Available


Martin Heat & Air Blog

Why Is My Heat Pump Only Working in One Mode?


The biggest advantage of using a heat pump for your home comfort is that it can work as both an air conditioner and a heater. You only need to make an adjustment to the thermostat to change the heat pump from one mode to the other. Simple, and you get excellent energy efficiency along with your comfort.

But a heat pump can malfunction in a way that it won’t change modes (or seem like it won’t). If you find your heat pump trapped in one mode, you’ll probably need professional heat pump repair in North Myrtle Beach, SC. Heat pumps aren’t something you can fix as a DIY project!

What can cause this heat pump problem? We’ll look at the most common causes below.

A broken reversing valve

A heat pump works by making an important change to the standard air conditioning system. An AC circulates refrigerant so that it absorbs heat from inside the home and then exhausts that heat outside. A heat pump adds the ability to heat with a device called the reversing valve. This valve can control the direction refrigerant circulates. When it changes direction, it will move heat from outside and exhaust it inside.

The reversing valve can break so that the slider necessary to redirect refrigerant as it exits the compressor won’t change position and becomes stuck. This is often why a heat pump will remain in one mode. Professional HVAC technicians can solve this by repairing or, in most cases, replacing the broken reversing valve.

Thermostat malfunction

The issue may be that the thermostat controlling the heat pump isn’t able to communicate with it. A thermostat has a specific connection to the reversing valve separate from the other connections, so the thermostat may still seem to be operating normally in all other ways while unable to make the heat pump change modes.

The thermostat may also have a miscalibration so that it isn’t reading accurate indoor temperatures. In this case, it won’t signal to the heat pump to change modes when it’s supposed to. Professionals can repair lost connections or recalibrate the thermostat.

Clogged filter

This is a problem that you can solve on your own. If the air filter for the heat pump is extremely clogged, it will prevent the heat pump from moving enough air to operate in the mode you want it to. Slide the filter out of its slot and replace it with a clean one, and this might fix the problem. To prevent this issue from occurring in the future, change out the filter on a regular schedule of every 1–3 months.

Electrical malfunction

The control board for the heat pump is responsible for keeping all the components working in conjunction with each other. An electrical problem with the control board can lead to the heat pump failing in several different ways, including becoming stuck in one mode. You can’t work with the control board on your own, so please reach out to professionals to handle the work.

Call Martin Heat & Air for solutions to all your heating and cooling concerns. We’re more than HVAC services; we give you peace of mind. 

Comments are closed.