Heat Pumps
Can You Replace Just the Outside AC Unit?
By HVAC.com•March 7, 2025
As summer temperatures rise, your air conditioner becomes your best friend in keeping your home cool and comfortable. But what happens when your outdoor AC unit starts acting up? Is it possible to replace just the outdoor unit, or do you need to replace both the indoor and outdoor components at the same time?
While the idea of saving money by replacing only the outdoor unit might sound appealing, there are several factors to consider, especially with recent changes in refrigerant technologies. HVAC.com breaks it down to help you make an informed decision when it’s time to buy a new air conditioner.
Can You Replace Just the Outside AC Unit?
If your indoor and outdoor units are relatively new (typically less than five years old), and the outdoor condenser unit needs to be replaced prematurely, it may still be under warranty, making replacement a possible option if. However, several factors could lead to compatibility issues, making replacing both the indoor and outdoor units at the same the most sensible choice in almost all scenarios. Let’s explore why.
Refrigerant Compatibility
The main issue with replacing just the outdoor unit is refrigerant compatibility. Older air conditioners (typically manufactured before 2010) use R-22, commonly known as Freon, which was phased out due to its environmental impact and has not been produced in the U.S. since 2010. Newer systems, typically installed between 2010 and 2025, use more eco-friendly refrigerants like R-410A.
The problem arises when systems with different refrigerants are mixed. For instance, an older indoor unit using R-22 won’t be compatible with a new outdoor unit that uses R-410A or R-454B. Even if the units are from the same brand, the refrigerants and coil types won’t work together.
Starting in 2025, R-454B will replace R-410A in all new air conditioners and heat pumps as part of the HVAC industry’s effort to reduce environmental impact. While R-454B is more energy efficient and eco-friendly, older systems using R-410A won’t be compatible with these newer units.
Why Replacing Both Units at the Same Time Is the Best Choice
Replacing both your indoor and outdoor units at the same time might seem like a big expense, but it can help you avoid headaches and extra costs later on. A mismatched system can lead to several issues, such as decreased efficiency, voided warranties, and premature failure. Here’s why upgrading both units together is the best solution:
Better Energy Efficiency
When both units are replaced at the same time, they’re designed to work together harmoniously. This synchronization between components, like the evaporator and condenser coils, results in better energy efficiency. With a matched system, your air conditioner will use less energy to cool your home, ultimately saving you money on your energy bills.
Increased Comfort
Replacing both the indoor and outdoor units at the same time ensures a fully compatible system that provides consistent and even cooling throughout your home. With a matched system, you can enjoy a stable, comfortable temperature in every room, regardless of the season, eliminating the discomfort of hot or cold spots.
Longer Lifespan
When your indoor and outdoor units are properly matched, the entire system operates more efficiently, reducing strain on individual components. This helps extend the overall lifespan of your air conditioning system, meaning fewer repairs and a longer period of reliable performance.
Warranty Protection
Replacing both units at the same time also helps maintain your warranty. Many manufacturers require both the indoor and outdoor units to be replaced together for the warranty to remain valid. With a complete system replacement, you’ll have peace of mind knowing that if something goes wrong, you're covered without the risk of voiding your warranty.
The Cost of Replacing Your AC Units
The average cost to replace an entire AC system – including both the indoor and outdoor units – typically ranges from $3,300 to $7,800, depending on the brand, system size, and any additional features like smart technology. Replacing just the outdoor unit might seem like a way to save money, but the potential risks and inefficiencies aren’t worth the risk.
Why Replacing Both Units at Once Is the Smart Move
While replacing just the outdoor AC unit is technically possible in some cases, it’s not the ideal solution for most homeowners. The introduction of new refrigerants like R-454B in 2025, along with the risk of mismatched systems, means that replacing both units at the same time is often the most practical and cost-effective option. It ensures compatibility, improves efficiency, and maximizes the lifespan of your HVAC system.
Before making any decisions, consult with an experienced HVAC technician. They can assess your current system, help you understand the compatibility issues, and provide recommendations based on your home’s needs.