heat pump condenser outside of house with blue siding

Does your HVAC system have a heat pump condenser? Condensers are essential for central air conditioners, split-system, and mini-split heat pumps. Without condensers, these systems could not exchange heat with the outdoor air. Though both systems use condensers, air conditioner and heat pump condensers are not identical.

Heat pumps are energy-efficient heating and cooling systems that operate like air conditioners, using refrigerants to transfer heat between indoor and outdoor air. Unlike air conditioners, heat pumps use specific mechanisms to deliver warm and cool air to indoor spaces year-round. While both condensers have similar appearances, they can be distinguished if one knows what to look for.

Heat pump systems fail when condenser problems arise. Understanding the best locations for condensers, how to clean them, and the issues that cause condensers to malfunction is critical to a heat pump’s longevity and performance.

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What is a heat pump condenser?

A heat pump condenser is an air-source heat pump’s main outdoor component. The boxy unit resembles a split-system air conditioner, with aluminum fins lining the sides and a fan on top. The condenser cabinet contains the condenser coil, compressor, reversing valve, and other parts.  

How does a heat pump condenser work?

A heat pump condenser works like an air conditioner condenser in cooling mode. The compressor pushes the hot refrigerant through the condenser’s coil. The fan and metal fins assist in transferring the home’s heat from the refrigerant to the outdoor air.

The heat pump reversing valve reverses the refrigerant’s flow in heating mode, and the condenser becomes an evaporator. The refrigerant in the coil absorbs the outside air’s heat and moves it inside the house.

Heat Pump Condenser vs Compressor

The compressor is an essential component of heat pump and air conditioner condensers. Commonly considered the heart of these systems, the compressor pressurizes the refrigerant to force it through the refrigerant lines. Pressurizing the refrigerant also increases its temperature, which aids in the heat exchange process.

In cooling mode, the refrigerant absorbs the home’s heat at the indoor evaporator coil. The compressor’s internal moving parts create suction that pulls the warm refrigerant gas to the compressor through a hose. The compressor reduces the gas’s volume, pressurizing it and increasing its temperature. A second valve in the compressor opens when the gas reaches the correct pressure and discharges the refrigerant to the condenser coil.

heat pump illustration showing location of compressor

Best Location for a Heat Pump Condenser

Heat pump condensers are installed outside houses to exchange heat with the outdoor air. Heat releases from the condenser coil in cooling mode and absorbs through the coil in heating mode. Installing a condenser in a garage or other confined space reduces efficiency. The condenser would release heat into the area in cooling mode, incrementally increasing its temperature. In heating mode, the condenser would draw heat from the room and substantially lower its temperature.

Good airflow around condensers is essential. Shrubs, plants, fences, garbage cans, and other barriers should be kept three to four feet away from the units, and multiple condensers should be spaced apart. Sun exposure is another important consideration. Condensers should be installed in shaded locations or areas that don’t receive full sun.

Common Issues for Heat Pump Condenser Not Turning On

Heat pumps operate like air conditioners, using refrigerants to exchange heat with the outdoor air. Anything that impedes the heat transfer, such as airflow blockages or grime on the coil, can cause heat pump systems to overheat and shut down.

Furthermore, condensers comprise many components that work together and keep the systems running. Problems with any of the elements, such as the fan, the motor, the refrigerants, the electronics, or the sensors, can prevent condensers from operating.

Specific issues prevent heat pump condensers from turning on:

  • Fan motor failure

  • Overheating

  • Energy deficiency

  • Freezing up

  • Air quality

heat pump fan motor failure

Fan motor failure

The fan motor powers the condenser fan to circulate air through the unit. Fan motor failure can cause the compressor or high-pressure trips to overload and shut down. Several problems can cause the fan motor to fail: debris obstructing the airflow through the condenser can cause the motor to overheat, faulty electrical controls can interrupt signals to the motor, and fan motors can wear out over time.

heat pump overheating due to debris in condenser


Condensers release the refrigerant’s heat into the outside air, but the unit can overheat and shut down if the airflow is obstructed. Dirt and debris in the condenser commonly induce overheating. Inappropriate installation locations and damaged controllers or sensors are additional overheating causes.

heat pump condenser shut down due to energy deficiency

Energy Deficiency

Condensers shut down when they become energy deficient. Specifically, the energy consumption increases by 60%, and the heating capacity reduces by 40%. Dirty outdoor coils typically cause energy deficiency.

heat pump freezing up

Freezing Up

Heat pumps have systems to melt the frost that forms on their coils in winter. Substantial ice on the unit reduces efficiency and often indicates underlying issues. A heat pump freezing up can have several origins:

  • Low refrigerant - Outdoor and indoor coils freeze when the refrigerant is undercharged, and the system absorbs less heat. Refrigerants don’t diminish over time unless there is a Freon leak. HVAC professionals must handle refrigerant leaks.
  • Water on the outdoor unit - Water from melting snow and leaky gutters can freeze on the coil, forming a thick ice layer that the defrost function can’t melt. Find the water’s source and eliminate it. Don’t chip away at the ice to remove it. Instead, turn off the electricity supply to the heat pump at the circuit breaker panel, and pour warm water over the ice to melt it.
  • Malfunctioning fan motor - The condenser fan pulls air across the outdoor coil to facilitate heat transfer. Less airflow due to a broken fan motor can cause the coil to freeze up. Schedule an appointment with an HVAC service to have the fan assessed, repaired, or replaced.
  • Faulty defrost timer - The defrost timer initiates the heat pump’s defrost cycle when the sensor detects a low coil temperature and repeats the processes regularly. A defective timer that runs irregular cycles causes the coil to freeze up. An HVAC professional will be able to pinpoint the problem and offer solutions.
dirty heat pump condenser affecting air quality

Air Quality

Poor air quality in the condenser from dirt on the coils and fan can affect its functions. Condensers should be regularly cleaned to keep them operating efficiently.

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How to Clean Heat Pump Condenser

Heat pump maintenance preserves efficiency, prevents problems, and prolongs system lifespans. Perform upkeep twice a year at the start of the heating and cooling seasons.

  1. Turn off the condenser’s power supply at the outdoor power box on an exterior wall near the unit or the circuit breaker switch on the main breaker panel.

  2. Trim branches, grass, and other plants around the condenser unit. Remove nearby toys, furniture, and yard debris. Allow at least three feet of clearance on all sides.

  3. Use a screwdriver or cordless drill to remove the screws securing the condenser’s outer cage or panels. Avoid banging the cage against the delicate metal fins.

  4. Use one of the following methods to clean the fins and coil:

    1. Gently wipe away dirt and debris from the unit’s exterior with a soft brush or the brush attachment of a shop vac. Avoid bending the fins.

    2. Clean the coil with a soap and water solution or an outdoor coil cleaner. If possible, remove the unit’s top grille before beginning. The fan is sometimes attached to the grille, in which case, prop it open without straining the electrical or leave it in place. Avoid spraying the fan and the electronics with water.

      Spray the unit’s exterior with the soap and water mixture or the outdoor coil cleaner in a spray bottle. Then, rinse the unit with a garden hose sprayer attachment from the top down. Never spray water directly at the fins or from the sides to avoid bent fins. Next, spray water outwards from the inside of the unit if the top grille is removed.

  5. Replace the top grille, panels, or cage. Restore the condenser’s power.


Heat pumps and air conditioners use condensers to exchange heat with the outdoor air. Both types of condensers are installed outside and have appearances. Condensers are large, squarish units with fans on top and metal fins on the sides. These units use compressors to pump refrigerants through their systems.

Heat pump condensers utilize reversing valves to cool and heat houses, whereas air conditioners can only cool homes. Locating the reversing valve inside the unit is one way to distinguish a heat pump from an air conditioner.

Condensers should be installed outside, away from direct sunlight, with ample space around them. Branches and organic material should be regularly trimmed back, and nothing should be situated within three to four feet of the units.

Condenser problems (fan motor failure, overheating, energy deficiency, freezing up, poor air quality) can cause heat pump systems to fail. Cleaning the condenser twice yearly preserves efficiency, prevents problems, and prolongs the system’s lifespan.

Frequently Asked Questions

Will a heat pump work without freon?

Heat pumps will operate without Freon but won’t cool and heat homes. Running a heat pump with low refrigerant is pointless, and it can damage the system’s components.

What does a heat pump condenser look like?

Heat pump condensers are installed outside houses. They are cubical, metal units with fins on the sides and fans on top. Heat pump condensers are nearly identical to air conditioners but include reversing valves to heat and cool houses.

To locate the reversing valve, turn off the system and go to the outdoor unit. Look through the top grille for a cylindrical brass mechanism with three fittings on one side. If you don't see it through the top grille, the reversing valve might be concealed behind an access panel outside the coil.

How to tell if a condenser is a heat pump?

There are a few ways to tell if the outdoor unit is a heat pump or air conditioner condenser:

  1. Check the outdoor unit's label. Look for the words "heat pump." Air conditioners are labeled "central cooling air conditioner" or "condensing unit." You can also type the label's manufacturer and model number into an Internet search engine.

  2. Locate the reversing valve. First, turn off the system. Look through the outdoor unit's top grille for a cylindrical brass mechanism with three fittings on one side. If you don't see it through the top grille, the reversing valve might be concealed behind an access panel outside the coil.

  3. Check if the condenser runs when the heat is on. First, set your thermostat to heat, and raise the temperature to ten degrees. Then, stand near the outside unit. You have a heat pump if the outdoor unit runs when the heat is on.

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1 comment

Geraldine Atkins

Geraldine Atkins

My condo has put my HVAC unit on the roof of my building. According to your article, "Condensers should be installed in shaded locations or areas that don’t receive full sun.” The weather is getting hotter in the summer, what should I do?

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