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PRK Services, Inc. Blog

Why Won’t My Heat Pump Switch to Cooling Mode?


If you have a heat pump, you’re probably quite pleased with it. The efficiency in particular is probably a delight. But the thing that really sets a heat pump apart is that it can cool your home during hot weather and heat your home during cold weather.

Unfortunately, no system works perfectly forever and problems can occur with that switching process. The reversing valve is the component responsible for switching between modes and we’d like to tell you all about it, including what to do if it’s not working. 

Reversing Refrigerant Flow

A heat pump and an air conditioner operate the same way. They pump refrigerant through coils, taking in heat in one area and dispersing it somewhere else. In hot weather, both a heat pump and an AC unit disperse that heat outside. In cold weather, the heat pump’s refrigerant flow can be reversed, dispersing heat indoors. The reversing valve makes this switch possible. 

This component looks like a brass instrument. There are three openings for refrigerant to flow through. Two of them are covered by a slider, closing the loop to connect them. When you switch modes, the slider changes which two are covered. The slider is only able to do this because of a component called a solenoid.

The Solenoid

It takes pressure to move the slider, and the solenoid applies that pressure. This is a coil-shaped, magnetized wire.

  • When an electric current is passed through the solenoid, it is energized, creating a magnetic field that puts pressure on the slider.
  • It moves into the position that lets refrigerant flow in the direction which disperses the heat outdoors.
  • Without this current, the solenoid is de-energized.
  • The slider moves to the other side, into the “at-rest” position.
  • Now the refrigerant can only flow in the direction which disperses the heat indoors.

Without the solenoid’s magnetic field, the heat pump cannot cool your home, and without the electric current, the solenoid can’t create the magnetic field.

The Electric Current

The current is created when a few key pieces fall into place. The thermostat registers the temperature in your home and signals that it is too high, and it’s time for the compressor to kick on and circulate that cooling refrigerant. That signal requires an electrical connection, so the thermostat’s communication can reach the solenoid. And of course, the solenoid must also be functional. Any of these three steps in the process can fail, de-energizing the solenoid and leaving your heat pump unable to switch to cooling mode. 

Professional Heat Pump Repairs

If you have a heat pump stuck in heat mode, you need professional repairs. Is the thermostat causing the problem? Has something come loose in the wiring? Or does the solenoid need to be replaced? A qualified technician can make the precise diagnosis and get your heat pump right back into cooling mode. There’s no need to suffer with a heat pump that only does half its job, so reach out right away.

Contact PRK Services, Inc. today for all your cooling and comfort needs.

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