If you've been told by a technician that you need to replace both of your AC units, you're probably wondering if it’s possible to just replace the outside AC and still use your current indoor unit to save money.
Here’s our recommendation: You should replace both the outdoor and indoor units together for the following reasons:
- Old indoor units are incompatible with new outdoor units
- Mismatched indoor and outdoor units lead to serious problems
- Replacing only one unit can void the manufacturer warranty
In this blog, we’ll go into more detail about each of those reasons. We’ll also share one exception when you may be able to replace just the outdoor unit.
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Reason #1: Old indoor units are incompatible with new outdoor units
If your current AC is 10+ years old, it’s going to be near impossible to find a new outdoor unit that’s compatible with your old indoor unit.
Here’s why: Old air conditioners use an outdated kind of refrigerant (the liquid substance that cools your home’s air) called R-22. Because it is hazardous to the environment, R-22 is no longer produced or imported in the U.S.
Today, all new air conditioning units use a more environmentally-friendly refrigerant called 410A. AC units that use this new refrigerant are not compatible with units that still use the old R-22 refrigerant. That means that any new outdoor unit you buy won’t work at all if your old indoor unit still uses R-22.
Reason #2: Mismatched indoor and outdoor units leads to serious problems
Even if you could find an outdoor unit that uses the same refrigerant as your old indoor unit, we would still advise against replacing only the outdoor unit because it would likely create a mismatched system.
What do we mean by a “mismatched” system?
A mismatched AC is when the outdoor and indoor units are not perfectly compatible with each other, such as:
- An outdoor unit with condenser coils that does not match the size of the evaporator coil (indoor unit)
- An outdoor unit with a different SEER rating than the indoor unit
- An outdoor unit made from a different manufacturer than the indoor unit
If you mismatch your outdoor and indoor units, you could face serious problems, such as:
- Reduced energy efficiency (which means higher monthly energy bills)
- Extra wear and tear on AC components
- Premature system failure
- Decreased indoor comfort
The AC, Heating and Refrigeration Institute (AHRI) tests thousands of indoor and outdoor units each year to verify they are properly matched. To find out if a particular outdoor/indoor combo is matched, you can ask the contractor who installs your AC for an AHRI Certificate of Certified Product Performance. Or, you can ask for an AC system’s Certified Reference Number and search for it in AHRI’s database online.
Reason #3: Replacing only the outside unit can void your manufacturer warranty
When your AC was first installed, it came with a warranty from the manufacturer that would cover the cost to replace parts that fail because of a manufacturing error.
However, your outdoor and indoor units must be matched for this warranty to be valid. If you replace your outdoor unit and it doesn’t perfectly match your indoor unit, the manufacturer likely won’t cover any future repairs or replacement parts.
One scenario when it’s okay to only replace the outdoor unit
If your current AC is new (1 to 5 years old), it may still be covered by the manufacturer warranty. In this case, it’s worth investigating to see if an outdoor unit replacement could be covered by the manufacturer.
If replacing your outdoor unit is covered by the warranty, the manufacturer will send a replacement outdoor unit that will be totally compatible with your current indoor unit.
To find out if your manufacturer warranty is still valid, go to your outdoor unit and locate the metal panel on the side of the unit. There you will find the model number of your AC. Then, go to the manufacturer’s website and search for your AC model number.
If you can’t find your AC’s warranty info on the website, contact the manufacturer directly or an HVAC contractor for assistance.
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We know buying a new outdoor and indoor unit at the same time is expensive. However, buying a matched system now will save you lots of money in the long run.
At Shafer, our goal is to help you find the perfect AC that fits your home’s cooling needs and your budget. Our comfort advisors will never sell you equipment you don’t actually need, and we offer flexible financing options.
To learn more about our AC replacement process, visit our air conditioner installation page.