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Serving the South Puget Sound and Western Washington Areas Since 1976

Serving the South Puget Sound and Southwest Washington Areas Since 1976

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Sunset Air Blog

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


It’s that time of year again—the time where we rely on our heat pumps to do the other half of their job—provide your home with steady cooling throughout the summer. With the simple switch on the thermostat from heating mode to cooling mode, the heat pump that kept you warm for so long during our cooler months should change over to become a powerful cooling system for summer.

What’s that? You switched your thermostat to cooling mode, but the air from your vents isn’t cool? It’s still rather lukewarm or even warm? Well, you certainly have a problem on your hands, but not an insurmountable one! We are here to help.

Below, we’ll cover a few reasons that your heat pump may not be able to switch over to cooling mode. Whatever the cause of this problem is at the end of the day though, remember that you need a professional to manage it.

You May Have a Broken Reversing Valve

The reversing valve of your heat pump is the component that changes the direction that refrigerant flows through the system after it exits the compressor—it goes one direction to provide heat and the other direction to provide cooling.

This is the main difference between a traditional central air conditioner and your heat pump. Unfortunately, if the reversing valve malfunctions or breaks, then your heat pump will become stuck in one mode until you have the valve professionally replaced.

You Might Have a Miscalibrated or Malfunctioning Thermostat

Your thermostat might indicate that it has, in fact, turned to cooling mode. However, if the thermostat somehow lost connection to the heat pump system due to loose or frayed wiring, then nothing that you do with the settings will switch the heat pump out of heating mode.

Our professionals can restore your thermostat’s connection to the system. You might also consider replacing your thermostat with an upgraded model like a WiFi or smart thermostat!

You May Have a Refrigerant Leak

Refrigerant is the chemical blend within all air conditioning system types that makes the cooling process possible. There’s a still common misconception that refrigerant is something that “runs out,” as gasoline does from a car. But in reality, your heat pump is supplied with enough refrigerant to ideally last its entire lifespan upon installation.

So if your system is losing refrigerant, it means it has a leak. And a refrigerant leak will absolutely make the air coming through your vents seem warmer than it should be. So it may not be that your heat pump didn’t switch to cooling mode, but rather it simply can’t cool, even in cooling mode.

Listen closely for a hissing or bubbling sound. This is the noise you’ll hear if you are, in fact, experiencing a refrigerant leak. Refrigerant leaks are more common in older HVAC systems, so this is especially important to consider if your heat pump is 10-15+ years old.

Reach out to Sunset Air today for quality service for your air conditioning and heating in Puyallup, WA.

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