Heat pumps have a unique construction and operation that sets them apart from other heating systems. This also happens to make their repair needs unique. Though you should always call a professional HVAC technician to address any issues with your heating system, it pays to know a bit more about how your heating system works. With that in mind, take a look at these repairs that your heat pump may need.
Broken Reversing Valve
The reversing valve is a 4-way junction in the refrigerant line between the indoor and outdoor units of the heat pump. This valve determines which way the refrigerant flows through the system, depending on the position it’s in. This is what makes the heat pump capable of both heating and cooling functions. The valve is comprised of a chamber that contains a slide. This slide has two positions, one for each refrigerant direction. Attached to the slide is an electromagnet called a “solenoid.” When the solenoid is charged, it pulls the slide to one side of the chamber. When the solenoid is not charged, the slide drops to the default position.
A reversing valve can break in two primary ways. The first way is that the slide becomes stuck in the chamber, preventing it from directing the refrigerant flow. The second way is that the solenoid loses its magnetism, rendering it unable to pull the slide from one side of the valve to the other. If the slide is stuck, a technician simply has to open the valve and free it. If the solenoid loses its magnetism, however, it will have to be replaced.
Broken Defrost Cycle
During cold days, the outdoor unit of the heat pump can have ice buildup on the outside of the casing. If the ice manages to cover most or all of the unit, it will cut off the unit’s ability to siphon heat. Normally, the heat pump uses a defrost cycle to melt the ice off of the unit. If you notice that your outdoor unit is mostly or entirely covered in ice, however, that means the defrost cycle isn’t working. You’ll need to call a professional to fix it.