Is It Okay To Replace Just the Outside AC Unit in My Home?

Conroy Baltimore
Written by Conroy Baltimore
Reviewed by Robert Tschudi
Updated May 17, 2022
The outside AC unit in a house’s backyard
Photo: galinast / iStock / Getty Images Plus / Getty Images


  • Replacing only your outdoor AC can lead to system inefficiency.

  • Installing a new AC costs between $3,800 to $7,500.

  • Consult with an HVAC technician to determine the best repair methods.

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When summer rolls around, you blast your AC to keep cool from the sweltering heat. However, this year is different. Your outdoor AC unit is well over its intended lifespan and is causing issues with your cooling solutions. Now, you’re left with a dilemma; should you replace just the outdoor unit or both AC units? We’ll provide further insight into that question below.

Can You Replace Just the Outside Air Conditioning Unit?

While you can replace just your outside unit, we highly recommend replacing both AC units when one is giving you problems. Why? Let’s count the ways.

Out With the Old (Refrigerant), In With the New

If you have a unit over ten years old, it will be next to impossible to find a compatible outdoor unit with your indoor one. Older ACs use a refrigerant called R-22, but the US no longer manufactures it. According to the Environmental Protection Agency, they halted production after learning it’s harmful to the ozone layer.

Newer air conditioners use R-410A, R-407C, and R-134a to enhance cooling solutions and energy efficiency. Unfortunately, you can’t mix and match your AC units as you do with socks. If you have an older indoor unit using R-22, it won’t be compatible with an outdoor AC that uses R-410A. 

The Effects of a Mismatched System

HVAC compatibility doesn’t stop at refrigerant—other factors like your AC coils and valves, the SEER rating, and manufacturers ensure your AC units function correctly.

“We once only changed out the outer part of a split system, but that was because the inside component was impossible to access, as the homeowner had done remodeling that occluded the inside unit,” says Bob Tschudi, Expert Review Board Member and general contractor in Raleigh, NC. “We were able to get the inside unit motor replaced but not the housing and electronics. The homeowner understood that the impending replacement of the inside unit would involve wall removal and changes to the remodeled space.”

Decreased Efficiency

Your AC has two sets of coils—evaporator and condenser. If these coils don’t match, efficiency will suffer. Also, your AC valve—which controls refrigerant flow for your coils—will need to work harder. 

As a result, replacing the outdoor unit alone can cause reduced energy efficiency, uncomfortable temperatures, wear and tear on your system.

Lower SEER Rating

SEER or Seasonal Energy Efficiency Ratio measures how efficiently your air conditioner cools. The higher the rating, the more efficient your unit is. 

However, replacing the outdoor AC alone will cause your unit’s SEER rating to drop, resulting in an inefficient system and all that comes with it.

Voided Warranties

During initial AC installation, there’s usually a warranty that covers defects or breakdowns. It only applies to the unit manufacturer.

If you replace only one part of your AC, it will void your warranty since the manufacturer isn’t the same. 

Premature Cooling Failures

As you know, regular HVAC maintenance can help your system last between 10 and 15 years. That lifespan gets significantly shortened when there’s system incompatibility due to only replacing one unit. Your system will be working twice as hard to meet your cooling needs.

You’ll also have frequent HVAC repairs on your hand, which could add up over time. Avoid this by replacing the indoor and outdoor ACs at the same time.

What Are the Benefits of Replacing Both Inside and Outside AC Units?

If your outdoor unit is giving you trouble, it would be better to replace the indoor one too. The cost to install a new AC ranges between $3,800 to $7,500. Prices depend on factors such as:

  • Location

  • AC type

  • Manufacturer

  • House size

But you’ll reap benefits from new AC installation like:

  • Saving on cooling costs

  • Increasing comfort in your home

  • Keeping your warranty active

“When we do a remodel, especially on an older home, we always fully replace all components of the HVAC system, including the inside-outside split system units and as much ductwork that we can access without tearing out walls,” says Tschudi.

When Is Replacing One Part of the System a Good Idea?

Although it’s beneficial to replace both AC units when your outdoor unit is causing issues, sometimes replacing only that part can be an option. For example, if your air conditioner is about 3 to 5 years old, it might still have warranty coverage.

Check with your manufacturer to see if they’ll cover the replacement of the outdoor unit. If so, a compatible outdoor unit will get sent to your home since the indoor unit is relatively new. 

Anything older will result in both units needing replacement. However, you should hire an HVAC technician and consult with them to figure out the best solution.

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