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Serving Northern California Since 1946

Serving Northern California Since 1946


DeHart Plumbing, Heating, and Air Inc. Blog

What’s Going On When a Heat Pump Won’t Heat


Temperatures may not get as chilly here as they do in the Midwest or Northeast, but if the last couple of weeks have been any indication, it does get cold. This means that furnaces and heat pump systems have been turning on for the first time in months recently. If you have a heat pump in your home, then it gets a lot of use… but you most recently used it in cooling mode, right? All it takes to switch it to heating mode is a quick adjustment on your thermostat.

But what if you adjust your thermostat to get heat from your heat pump, and nothing happens? Perhaps you’re still getting cooled air from the vents, or maybe the air feels like it is still room temperature. This is a clear indication that something is wrong. The problem might be something simple, or it could be more complex. Read on as we uncover what could be going on when your heat pump won’t heat.

A Clogged Air Filter

The air filter that comes standard with your HVAC system or heat pump is in place to protect the system from dust, dirt, and other debris that can get inside and build up on the system’s components. What happens is that this air filter can get too clogged up with that debris if it is not changed often enough (every 1-3 months, depending on the type of air filters you have).

When this happens, airflow will be restricted going into your heat pump. This will impact the entire operation, and as a result the air you feel coming out of the vents may be lukewarm.

A Miscalibrated Thermostat

Perhaps you’ve adjusted the thermostat to the temperature you need it to be, but it’s not turning the heat pump over to heating mode. It may be that it is misreading the temperatures in your home. Fortunately, recalibrating a thermostat is a relatively easy problem for our professionals to fix.

Before you give us a call though, make sure your heat pump is actually set in heating mode at the thermostat. This may seem obvious, but it’s entirely possible that a family member adjusted the settings on the thermostat if they have different preferences than you.

A Broken Reversing Valve

If you’ve checked on the air filter and the thermostat, and neither of them is the culprit, then the most likely cause of your trouble is a broken reversing valve. The reversing valve is the component responsible for enabling the heat pump to work as both a heating and cooling unit. The valve, when activated, reverses the flow of refrigerant throughout the system, which is what transfers heat.

Like any other mechanical component, it can break or become stuck in one position, locking the heat pump into its current mode. Unfortunately, this isn’t a problem that can be fixed easily—you’ll want to give our team a call to help.

For quality heating services in Modesto, CA, contact DeHart Plumbing, Heating, and Air Inc. today!

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