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Premier Heating & Air Blog

How Long Should My AC’s Compressor Run?


One of the small pleasures of the summer season is the satisfying thunk noise of the compressor in an air conditioning system turning on. As this part of the AC goes to work, it means cool, refreshing air will soon flow from vents around the house. 

If you’ve lived with a central air conditioning system before, then you’ll know its compressor doesn’t run constantly when you have the air conditioner turned to cool off the home. Instead, it runs periodically and then powers down for a stretch. These periods are known as cooling cycles, and they help to keep the temperature in a house from becoming too cold and to prevent the compressor (the most powerful part of an AC and the one that uses the most electricity) from overheating. But how long should the compressor run at a time?

This is an excellent question!

The short answer: 15 to 20 minutes. That’s the average time for an air conditioner to complete a cooling cycle and provide even comfort to a house. 

But we’re also providing a long answer because when a compressor begins to run for longer or shorter cycles, it can mean something is wrong. Often, unusual compressor runtimes require HVAC professionals to see if the system needs air conditioning repair in Conyers, GA

When the compressor runs longer…

Did you wonder how we could give such an exact compressor runtime? It’s because any AC system that was sized properly for a home will require that length of time for full cooling. When we install an AC, we carefully match its cooling capacity to the house so the compressor will run in regular cycles. 

So if you notice that your AC’s compressor always runs longer, say 30 or even 40 minutes, it’s a warning that the air conditioner is underpowered. This often occurs if an amateur did the installation and failed to size the system correctly. 

A compressor running too long can also indicate a repair problem: a malfunctioning thermostat that’s reading incorrect temperatures, a stuck motor relay, a frozen evaporator coil, or dirty condenser coils. You’ll want pros to find out what’s wrong so the AC will stop draining extra power and wearing down rapidly.

When the compressor runs shorter…

There’s a specific name for this problem: short-cycling. Not only does the compressor shut down too quickly (often in less than 10 minutes), but it quickly starts back up again and enters into a rapid start-stop pattern. This may also result from a poor installation that sized the air conditioner incorrectly—except, in this case, the AC is too powerful. An oversized air conditioner will lower the temperature too fast and cause the cooling cycle to be cut short. 

There are many other sources of short-cycling: another thermostat miscalibration (this time in the other direction), leaking refrigerant, blocked vents, a dying compressor, or an AC that’s too old.

We’ll see that you have an AC that works right!

No matter if your AC’s compressor runs too long or too short, we can diagnose the trouble and find out what repairs will fix it or if you need a replacement AC. 

Experience the Premier Difference! Premier Heating & Air has been family-owned and operated since 2001.

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