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Miami AC Guide: Why Short Cycling on an AC Unit Can Decrease Efficiency


Your Miami air conditioner’s compressor is more efficient the longer it is on. In fact, anything less than 5 minutes shows a sharp and sudden decrease in efficiency, largely due to how long it takes for the compressor to start cooling the air. It takes time to compress refrigerant and start removing moisture and heat. It takes at least five minutes for condensate to start running down the coil to the drain. If it cannot do this it simply evaporates back into the air supply and the efficiency and comfort level go down.

Generally speaking, an air conditioner is set to run on cycles that are as long as possible. So, if the heat load on a hot day for your air conditioner is only 50%, your system will turn on for 50% of the hour, turning on for 10 minutes, then off for 10 minutes, then on for 10 minutes at so on. However, if your air conditioner is sized to reach a higher percentage – closer to 75% on a particularly hot day – the system will remain on much longer.

On the flip side, if your system is not working properly or if it is too large, it can short cycle, meaning it produces a lot of cold air and then turns off after 5 minutes. That, in turn, means it can’t reach the efficiency levels it should. While part of this has to do with proper design of your HVAC system, another part is related to the operation of that system. Two-stage compression can help with this as well by running the system at a lower level if it is not too hot outside but you still need air conditioning.

If you notice your Miami air conditioner running on short cycles, it is important that you call Air On Demand to inspect it. While it could be a design issue, it could also be related to a bad thermostat, a refrigerant leak or even a problem with your compressor. In some cases, a simple fix and an upgrade to your thermostat can eliminate the issue. In others, replacement may be needed.