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Johansen & Anderson Inc Blog

Why Won’t My Heat Pump Switch Modes?


A heat pump is very much like an air conditioner. Almost all of the components are the same or very similar. This means that when there’s a problem with how it’s working, chances are, it is one of the same problems that air conditioners encounter. This could be something like a problem with the blower fan motor, or refrigerant leaking from the coils somewhere.

However, there is one type of problem that heat pumps can have which is totally different from anything you’ve had to deal with from an air conditioner before. This is because of the one way that your heat pump really differs from an air conditioner. A heat pump can switch between heating and cooling with a component called a reversing valve. This part can fail, leaving your heat pump stuck in one mode.

How the Heat Pump Reversing Valve Works

The purpose of the reversing valve is to change the direction in which the refrigerant flows through the system of coils. In one direction, it absorbs heat from indoors and disperses it outside, and when the direction is switched, it does the opposite. To accomplish this, it needs to uncover or block certain openings. This is done in a section of tube that looks a little like part of a trumpet, with three valves.

Inside this tube is a slider. If we consider the openings to be A, B, and C, in one position, A and B are open and C is closed. The refrigerant flows from A to B. When the slider moves into the other position, A is closed and B and C are open. The refrigerant flows from B to C. This controls which way it will flow through the rest of the system. 

How does the slider move? With pressure from a solenoid, a type of electromagnet. The solenoid either applies no pressure, leaving the slider in the “de-energized” position, or—when it receives an electric charge—it applies pressure and the slider moves to the “energized” position. Without the charge, the heat pump will heat your home. When it receives the charge, it will cool your home.

How the Heat Pump Reversing Valve Can Fail

If your heat pump is stuck in heating mode and won’t switch to cooling, chances are, the slider is in the “de-energized” position because the solenoid is not applying the necessary pressure to move it. Why? There are three possible reasons.

First is the solenoid itself. These don’t last forever and are vulnerable to extreme heat and moisture, and the component is in the outdoor unit, exposed to the weather. Second, there’s the electrical wiring that connects the solenoid so it receives the charge. Third, there’s the possibility that the charge is not being sent because of a lack of signal: a problem with the thermostat, and not the heat pump at all.

When you get heat pump repair in Lockport, IL, your technician will be able to accurately diagnose the specific cause of your stuck reversing valve. Whether it’s the solenoid, the wiring, or the thermostat, it can be corrected so you can get back to enjoying all that your heat pump has to offer.

Call J&A today, Sleep-tight tonight!

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