Heat Pump Reversing Valve Diagnostics

A heat pump consists of several moving parts, each of which serves its own purpose for helping the unit function. The reversing valve is what toggles your heat pump from cool to hot air and back again. If there is a problem with this part, it can mean no working heat in the winter and no cool air in the summer. While the problem with your unit could be a variety of other issues, it's important to determine whether or not it is related to the reversing valve.

Diagnosing the Problem

In many cases, the reversing valve simply gets stuck in one position due to debris or something else clogging it up. Since your outdoor unit is outside, it doesn't take much for dirt, leaves, or even small twigs to make their way in and eventually cause the valve to stick. Another problem the valve may face is leaking refrigerant. This can be a bit more difficult to troubleshoot since other parts of the heat pump can also leak this material. The compressor is a common suspect as well. The issue of a stuck or leaking valve are the two most common problems, so if you know how to remedy the issue, your unit should be back to normal.

Fixing a Stuck Valve

If in fact your reversing valve is simply stuck, try to use a leaf blower to blow excess debris out of your unit. You can also try to do this using a high powered wet/dry vac. If it's matter of a few bits of debris, this should correct the problem within a few minutes. If it's just stubborn debris you can easily see, take a flat head screwdriver and try to pry the debris loose. If your valve is stuck due to something else, you may have to do more work to relieve it. Use a powerful magnet and place it near the pilot valve. If it shows resistance, then it's possible the pilot valve is not receiving enough power in order to operate the reversing valve. Take an electrical multimeter and check the current. If it does not match the manufacturer's specs, the pilot valve may need to be replaced or rewired. 

Fixing a Leaky Valve

In order to determine if the valve is leaking, you'll need to eliminate other possibilities first. A common problem with leaking heat pumps is that the refrigerant has flooded the evaporator coil. If it's the compressor, you will want to run the heat pump without the use of the compressor motor for a few minutes and check to see if the liquid is building up. Use a pressure gauge to monitor this, and when the gauge gets to the highest reading, turn the system off. You should hear gases start to escape, and then you can visually inspect to see if they're coming from the reversing valve or the compressor. This will help you determine which part is leaking and will need to be replaced.

If you find the problem may be more complicated than you expected, contact a local specialist, such as Lowry Services: Electric, Plumbing, Heating & Cooling.