Can I Replace the Outdoor Unit on My Older Air Conditioning System with a Newer Model?

In some instances one part of a split-system air conditioner will stop working even while the other half continues to function. This happens most frequently with the outside cabinet (the condenser unit), where the compressor and the condenser coils work together to dispatch waste heat removed from inside the home.

If this ever happens to you, and you can find an exact duplicate, you certainly can change outer cabinets without disturbing the interior section of your air conditioner. But if your air conditioner is old it might occur to you to look for a more modern condenser unit, which would be more energy-efficient than your old one and could save you money as a result (you assume). You may have heard this is possible and technically you’re correct, it is.

But if such a thought ever enters your mind you should send it into exile immediately. Just because you can do something doesn’t mean you should, and that is definitely the case here.

Split-System Chaos and the End of Your Air Conditioner

HVAC technology is ever-evolving and always in the direction of faster operation and greater efficiency. In comparison to older models, for example, modern condenser units feature coils that have larger surface areas, more aerodynamically correct geometry, improved tubing and an overall performance profile that dwarfs anything manufactured 10 or 20 years ago.

This sounds great, but there is a fundamental disconnect between the past and the present that will cause trouble if you turn your old air conditioner into a half-modernized hybrid. With a system like this you’ll experience less efficient heat transfer and cooling, increased energy consumption, frequent breakdowns and finally catastrophic product failure.

This isn’t speculative—using standards established by the American Society of Heating, Refrigeration & Air Conditioning Engineers, manufacturers have tested various combinations of technologically mismatched air conditioning components and proved conclusively that mixed systems don’t work well and are essentially disasters waiting to happen.

In addition to poor cooling performance and excess energy usage, incompatibility between old and new AC components leads to imbalances in performance between inside and outside that will ultimately lead to compressor failure.

The aforementioned tests showed compressors were 45 percent more likely to fail in the first year if the outdoor and indoor units were not technologically compatible in every aspect, and even if compressors managed to survive longer they were still doomed to die young.

This Just In: Short Cuts Will Cost You More

While energy-efficiency is always good, the best way to get it with an HVAC set-up is to install a fully-integrated contemporary system. It will cost more in the short-term but in the long-term it is bound to save you money.

And if one half of your split-system air conditioner has already failed it’s a fair bet the other half isn’t in the greatest shape and may be nearing a meltdown anyway.

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