Yes, most heat pumps use refrigerant—often called freon—to move heat between indoors and outdoors

Heat pumps rely on a refrigerant fluid to absorb heat from one place and release it in another. The refrigerant circulates through a closed loop of copper tubing, changing between liquid and gas states as it moves through the system. This cycle is what allows a heat pump to pull warmth from outside air (even in cold weather) and push it into your home, or reverse the process to cool in summer.

The term "freon" is often used loosely to describe any refrigerant, though true Freon is a brand name for chlorofluorocarbon (CFC) refrigerants that were phased out decades ago due to ozone damage. Modern heat pumps use newer refrigerants like R-410A, R-32, or R-290, which are less harmful to the environment. The specific type your system uses depends on when it was manufactured and local regulations.

Without refrigerant, a heat pump cannot function. It is the working fluid that makes the whole heating and cooling cycle possible. If your system leaks refrigerant, the heat pump will lose efficiency and eventually stop heating or cooling altogether.

Key Takeaways

  • Heat pumps use refrigerant (a liquid that circulates through the system) to transfer heat, not to generate it directly like a furnace does.
  • Modern refrigerants are labeled R-410A, R-32, R-290, or similar codes—not the older "Freon" that was phased out in the 1990s.
  • A refrigerant leak will reduce heating performance and requires a technician to locate and repair the leak, then recharge the system.
  • The refrigerant itself does not wear out or get used up; it cycles continuously unless the system develops a leak.

How refrigerant moves heat instead of creating it

A heat pump does not burn fuel or use electrical resistance to make heat the way a furnace or space heater does. Instead, it moves existing heat from one location to another using the refrigerant cycle. In heating mode, the outdoor unit absorbs heat from the outside air (yes, even when it is cold outside—there is still some heat energy present), and the refrigerant carries that heat indoors through the copper lines.

The refrigerant changes state as it moves: it evaporates (turns to gas) in the outdoor coil to absorb heat, gets compressed to raise its temperature, then condenses (turns back to liquid) in the indoor coil to release that heat into your home. A valve then reverses the flow for cooling mode. This cycle repeats continuously while the system runs.

This is why heat pumps are more efficient than electric resistance heating in many climates—they move heat rather than creating it from scratch. However, efficiency drops in very cold climates where there is less outdoor heat to extract, and some heat pumps include a backup electric resistance heater for those conditions.

What happens if your heat pump leaks refrigerant

Refrigerant leaks are the most common reason a heat pump loses heating power. A small leak may cause the system to run but deliver less heat than normal. A larger leak can stop heating altogether. You may notice frost or ice building up on the outdoor unit, hissing sounds near the indoor or outdoor coil, or a sweet chemical smell around the system.

Refrigerant is sealed inside the system and should never need topping off during normal operation. If a technician tells you the system just needs a "recharge," ask them to locate and repair the leak first. Refilling without fixing the leak is a temporary fix that will fail again within weeks or months.

Repairing a refrigerant leak involves finding the hole (often in a solder joint or the coil itself), sealing it, and then refilling the system with the correct refrigerant type. This requires specialized equipment and certification, so it is not a do-it-yourself job. Costs typically range from a few hundred dollars for a small leak in accessible tubing to over a thousand for a coil replacement.

Different refrigerants and what they mean for your system

The refrigerant type matters for repair and replacement parts. If your heat pump uses R-410A (the most common in systems installed from the early 2000s through the 2020s), a technician must use R-410A to recharge it—mixing refrigerants damages the system. Newer systems are shifting to R-32 or R-290, which have lower environmental impact.

If your system is very old and still uses R-22 (the refrigerant in many units from the 1990s and early 2000s), you should know that R-22 production has been phased out in the United States as of 2020. Recharging an R-22 system is now expensive because the remaining supply is limited, and technicians may recommend replacement rather than repair if the leak is significant.

When you have a heat pump serviced, the technician will tell you which refrigerant your system uses. Write it down for future reference—it matters if you ever need repairs or if you sell the home and the next owner needs to service it.

Why heat pumps need refrigerant but furnaces do not

A traditional furnace burns gas or uses electric resistance coils to create heat directly. It does not need refrigerant because it is not moving heat from one place to another—it is generating it. A heat pump, by contrast, is a heat-moving machine, and refrigerant is the medium that does the moving.

This fundamental difference is why heat pumps are quieter and more efficient in moderate climates, but also why they require more complex maintenance. A furnace has fewer moving parts and fewer things that can leak. A heat pump has more components and more potential failure points, though modern systems are quite reliable when properly maintained.

Maintenance to protect your refrigerant system

You cannot prevent all refrigerant leaks, but regular maintenance reduces the risk. Have your heat pump serviced once a year, ideally before the heating season starts. A technician will check refrigerant pressure, inspect coils and tubing for corrosion or damage, and clean the coils so the system runs efficiently.

Keep the outdoor unit clear of debris, leaves, and snow. Blocked airflow forces the system to work harder and can damage the coil. Do not let vegetation grow directly against the unit, and do not store items on top of it. These straightforward steps extend the life of the refrigerant circuit and reduce the chance of a costly leak.

If you notice reduced heating performance, frost on the outdoor unit, or unusual sounds, contact a technician promptly. Catching a small leak early is far cheaper than waiting until the system fails completely.

Frequently Asked Questions

Can I add freon to my heat pump myself?

No. Refrigerant handling requires EPA certification and specialized equipment to measure pressure and charge the system correctly. Overfilling or underfilling reduces efficiency and can damage the compressor. A technician must do this work.

How long does refrigerant last in a heat pump?

Refrigerant does not wear out or expire. It cycles continuously through the system indefinitely, as long as there are no leaks. If your system is sealed properly, the original refrigerant charge can last the entire life of the unit—often 15 to 20 years or more.

What is the difference between R-410A and R-32 refrigerant?

R-32 is a newer refrigerant with lower global warming potential than R-410A. Systems designed for R-32 are slightly more efficient and environmentally friendlier. However, you cannot mix them—each system is designed for one type only. Technicians must use the correct refrigerant for your specific unit.

Will my heat pump still work if it is low on refrigerant?

It will run but deliver much less heat or cooling. Low refrigerant pressure causes the system to cycle on and off frequently, frost to form on the outdoor coil, and the compressor to overheat. Continuing to run a low-refrigerant system can permanently damage the compressor, so have it checked when ready if you suspect a leak.

Is refrigerant toxic if it leaks into my home?

Modern refrigerants like R-410A and R-32 are not toxic at the low concentrations that would escape from a small residential leak. However, they are odorless and colorless, so you cannot detect them. If you smell a sweet chemical odor near your heat pump, that is likely an additive used to help technicians locate leaks, not the refrigerant itself. Have the system inspected by a professional.