Seven signs you need a new AC unit

The seven that point to replacement

1. The compressor has failed. The single most expensive component. Out of warranty, replacing it is often 50–70% of a whole new system, on equipment that is already old.
2. It uses R-22. Pre-2010 systems frequently do. No new production since 2020, reclaimed stock only, and prices that make a leak repair genuinely painful.
3. Past 15 years with repairs stacking up. Three repairs in two years is the system telling you what the next few summers look like.
4. The house cools but stays clammy. Persistent humidity usually means an oversized system, a failing charge, or both. If it is sizing, no repair fixes it — the unit is the wrong unit.
5. Bills climbing with no rate change. Compare the same month year over year. Efficiency loss is gradual and easy to miss.
6. Rooms that were never right, and still are not. Frequently a duct problem rather than an equipment one — worth diagnosing before you buy anything, because a new condenser will not touch it.
7. An evaporator coil leaking out of warranty. Coil leaks tend to recur, and each recharge costs real money.

The three that are usually just a repair

• It will not turn on at all. Very often a capacitor, a contactor, or a tripped float switch on a clogged drain. Frequently a few hundred dollars.
• It is blowing warm air. Could be low refrigerant, a dirty condenser coil, or a frozen evaporator. All repairable on a system that is otherwise sound.
• Water around the indoor unit. Almost always a clogged condensate drain line. Cheap, common, and no indication whatsoever that the system needs replacing.

If you are being told a system under ten years old needs replacing because of any of the above, get a second opinion from a company that does repair work.

Four checks you can do yourself in ten minutes

None of these need a technician, and together they will tell you which list you are on.

1. Read the nameplate. The sticker on the outdoor unit gives the model, serial and refrigerant type. Age and refrigerant are two of the five real triggers, and they are written on the box.
2. Check the filter. A blocked filter causes low airflow, a frozen coil, and warm air at the vents — the exact symptoms people replace systems over. Change it and give it a day before concluding anything.
3. Look at the outdoor coil. If the fins are packed with grass clippings, cottonwood or dust, the system cannot reject heat. It is a cleaning job, not a replacement.
4. Measure the temperature split. A kitchen thermometer at a supply vent and at the return will do. A healthy system shows roughly 16–22°F of difference. Much less means low airflow or low charge; much more can mean restricted airflow.

What a second opinion should include

If a contractor has told you to replace, a genuine second opinion should produce four things. If it does not, it is a sales visit rather than a diagnosis:

• The specific component that has failed, and how they tested it.
• The refrigerant type and system age from the nameplate.
• A repair price, even if their recommendation is replacement. If they will not quote the repair, they are not offering you a choice.
• Warranty status checked against the serial number.

It is also reasonable to ask for photographs of whatever they found, particularly for a cracked heat exchanger or a failed compressor. A technician confident in the diagnosis will not mind.

What to do next

Find the age from the nameplate serial. Identify the refrigerant. If it is under ten years and the symptom is on the second list, call a repair company. If it is fifteen-plus with R-22 and a major component gone, get replacement quotes — ideally in the shoulder season, when you have time to compare them properly.

AC installation and replacement →