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Why Is My Heat Pump Constantly Running? A San Marcos Tech Explains

December 08, 2020

If your heat pump is running non-stop, you’re probably wondering whether it’s normal or if something is wrong with your system.

Don’t worry just yet—if your heat pump is running non-stop, it doesn’t necessarily mean there’s a problem. It could just mean that it’s an especially hot day.

You see, when temperatures rise above 90° F, your heat pump will naturally run longer to keep up with the increased cooling demand.

However, if the outside temperature is relatively mild and your heat pump is running non-stop, your heat pump may have one of the following problems:

  1. A dirty air filter
  2. Closed vents
  3. Dirty coils
  4. A refrigerant leak
  5. The heat pump is getting old

We’ll explain each of these problems in more detail, and give you troubleshooting tips and recommendations on when you should call a professional for help.


Think your heat pump needs a repair? Our trustworthy technicians are standing by, ready to help!


Problem #1: A dirty air filter

The first thing you’ll want to check if your heat pump is running constantly is your air filter.

You see, all air that goes into your heat pump to be cooled or heated must first pass through the air filter. If your air filter is dirty, it blocks air from entering the heat pump, which ultimately makes your system run longer.

A dirty air filter

Besides longer run times, a dirty air filter can also lead to problems such as:

  • A worn out fan motor
  • A frozen evaporator coil (in cooling mode)
  • Warmer air coming from the vents (in cooling mode)
  • Cooler air coming from vents (in heating mode)

What to do

Go to your air filter and check it to see if it is dirty. If it is covered by a thick layer of dirt, that’s a sure sign it’s time to replace it.

Problem #2: Closed or obstructed vents

Your heat pump uses 2 types of air vents to provide conditioned air to your home:

  1. Supply vents, where conditioned air enters your home.

A supply vent

2. Return vents, where indoor air is pulled into the heat pump to be heated or cooled.

A return vent

If these vents are closed or furniture is blocking them, they could be causing your heat pump to run longer than it should. We’ll explain why below.

The problem with closing supply vents

Closing supply vents increases pressure in your ductwork, which makes it easier for air to escape via leaks or disconnected ducts.

When air escapes out of the ducts, it ultimately makes your heat pump run longer to heat or cool your home to your desired temperature.

The problem with closing return vents

Similar to a dirty air filter, a closed or obstructed return vent prevents air from flowing into the heat pump to be cooled or heated. The less air that reaches the heat pump, the longer your system has to work to heat or cool your home.

What to do

  1. First, check all of the supply vents in your home and make sure they are open, even in rooms you don’t often occupy.
  1. Second, make sure the return vents are open and that no furniture is blocking them.

If your vents are open and unobstructed but the heat pump is still running constantly, you may have one of the remaining problems, which will likely require a repair from a professional.

Problem #3: Dirty coils

Your heat pump has two sets of copper coils that help it cool or heat your home’s air:

  1. The condenser coil (located in the outdoor unit)
  2. The evaporator coil (located in the indoor unit)

The evaporator and condenser coils in a heat pump

Over time, these coils can become covered in excessive dust or debris, which prevent them from cooling or heating your home’s air properly, which will result in the system running longer than usual to cool/heat your home.

In addition to longer run times, you may also experience the following problems if your coils are dirty:

  • A moldy smell coming from the indoor unit
  • Warmer air coming from the vents (in cooling mode)
  • Cooler air coming from vents (in heating mode)

What to do

We recommend calling a professional to inspect the coils to see if they are dirty. A professional will have the right tools to safely and thoroughly clean the coils.

Problem #4: A refrigerant leak

Refrigerant is a liquid substance your heat pump uses to transfer heat into your home (in heating mode) or out of your home (in cooling mode).

You can learn more about refrigerant by reading our blog, “How Does a Heat Pump Work in Cold Weather? A San Marcos Tech Explains.

Sometimes the lines that carry refrigerant between the indoor and outdoor units develop leaks, which lowers the amount of refrigerant in your system. If your heat pump is low on refrigerant, it will have to work overtime to cool or heat your home.

Besides longer run times, a refrigerant leak can also lead to the following problems:

  • A frozen evaporator coil (in cooling mode)
  • Hissing or gurgling sounds coming from the heat pump
  • Reduced cooling or heating power

What to do

Contact a professional to measure the refrigerant levels in your heat pump. If it turns out your heat pump is leaking refrigerant, a professional will need to find the source of the leak, repair it, and then refill your heat pump with the proper amount of refrigerant.

Problem #5: The heat pump is getting old

Finally, your heat pump could be running extra long because it’s nearing the end of its life.

As a heat pump ages, it slowly loses efficiency and parts start to malfunction, which cause the system to run longer and longer.

Most heat pumps last around 10 to 15 years on average. If your heat pump is 10+ years old, that could explain the longer run times.

What to do

If your heat pump is 10+ years old, you may want to start considering replacement. You may not need to replace your heat pump immediately, but if you start noticing frequent repairs and even longer run times, you should contact a professional for advice on a replacement system.

Need a heat pump repair from a trusted San Marcos pro?

If you need a pro to get to the bottom of the problem and figure out why your heat pump is running non-stop, call Reliable Air. We offer upfront, honest pricing and exceptional customer service for every heat pump repair.

Visit our heat pump repair page to learn more about what to expect when you hire us.

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