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When I Replace My AC Unit Does the Indoor & Outdoor Units Both Need Replacing?


Do you have to replace your entire AC or can you upgrade it one piece at a time? Here’s the answer from HVAC professionals.

Buying a new air conditioner? Let us at Blanton’s Air in North Carolina be the first to congratulate you. Whether your old air conditioner is broken or you just want to upgrade, replacing an AC unit is a perfect opportunity to shop smart and make an investment that will decrease your monthly energy bills, and keep your house cooler for longer, and more consistently (not to mention, with less environmental impact). But replacing an air conditioner can be confusing: Do you have to replace the whole AC? Or can you do it in increments, with just the outdoor, or indoor units? As your local heating and cooling professionals, we have plenty of opinions about this! Here’s what the HVAC pros have to say.

What Parts Are in An AC Unit?

First things first: We have to define the different components of an air conditioner. For the purpose of this article, we’re talking exclusively about central air conditioners — although portable or in-unit air conditioners are good options for small spaces, rental properties, or low budgets. This article features the 11 most common AC terms  — it’s a good place to start as you acquire the knowledge to become an HVAC pro.

Condensing (a little AC humor for you!) a lengthy topic into the basics: Your central air conditioner consists mainly of the outdoor unit and the indoor unit. The outdoor unit contains a compressor coil, condenser, and fan. The indoor unit contains the evaporator coil, while refrigerant lines connect the two units (AC refrigerant runs through the lines, and does the job of actually cooling the air).

What’s The Best Way to Replace an AC Unit?

The fact of the matter is this: It’s in your best interest (and the best interest of your pocketbook) to replace both the indoor and outdoor units at the same time. While you technically could upgrade them in parts, this strategy will likely backfire — or worse, not even work in the first place. Here’s why you should replace your AC unit all at once.

  1. Newer AC Units May Not Be Compatible with Old Units

    Like all types of technology, HVAC technology moves at lightning speed! What seemed cutting-edge ten years ago is old news today. This means that you’re inviting operating problems with mismatched units. To ensure an air conditioner that runs smoothly (and reliably), replace your AC unit all at once.

  2. You Could Cause a Problem with The Refrigerant Lines

    Older AC units rely on freon. But new air conditioners use a safer form of refrigerant. If you’re still cooling your house with freon (it’s unlikely but possible), then upgrading half of your AC to a new unit won’t work. (As a side note: If you DO have an old unit, but have repaired a leak in recent years, then your HVAC technician should have upgraded the refrigerant to a newer variety. But that’s no excuse not to upgrade now.)

  3. Older Units Can Cause Efficiency Issues

    Let’s face it: older technology just isn’t as efficient as new HVAC technology. If you’re still relying on 20-year-old air conditioning equipment, you’re definitely not getting the best experience possible. Investing in an entirely new unit when you replace your AC will allow you to buy smart. You may be surprised at how affordable some of the newer models are — and there’s always the option to shop for an ENERGY STAR-rated appliance, which may provide a tax kickback

  4. Replacing Just One Part of Your AC Unit Could Void The Warranty

    If you’re not ready to take the plunge and buy an entirely new air conditioner, you may be tempted to just upgrade the outdoor or indoor unit. But doing so could void the warranty, which will defeat the purpose of your savvy saving attitude.

Remember that buying an air conditioner is an opportunity to invest in long-term savings. That holds true whether you’re a first-time AC buyer, or you need to replace your AC unit with something newer or better. If you’ve ever broken a laptop or smartphone, you’ve probably heard that it’s better to buy new than to invest in fixing the problem. This isn’t always true for air conditioners (your local HVAC tech will tell you when it’s worthwhile to repair, and when you need to replace), but if you ARE going to replace, it is good business, eco, and efficiency sense to replace an AC unit all at once.

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