Why Is My AC Short-Cycling?
Everything is going fine, and then you notice your air conditioner is going on and off more frequently. You had it serviced before the season started and you thought everything was okay. Now it’s not working properly.
You’re wondering what is causing the constant on/off cycling and asking yourself “Why does my air conditioner start then stop?” Read on to find out some possible reasons it’s doing that and how to stop it from happening.
What is AC Short-Cycling?
AC Short-Cycling is an HVAC industry term for an air conditioner that has gotten stuck in the start-up cycle and turns on and off repeatedly without completing a full cooling cycle. On a normal cycle, the system will come on, run until it reaches the target temperature, and then shut off the compressor. This usually takes about 10 minutes. A system that’s short-cycling will only run for a few minutes and then shut off. It’ll come back on a few minutes later, shut off, and then repeat the cycle over and over. This causes the compressor to come on repeatedly, which can lead to early compressor wear and failure. It also robs you of a proper cooling cycle and your comfort.
What Causes an Air Conditioner to Short Cycle?
Dirty Air Filter
A dirty air filter will restrict airflow in your system and allows hot air to build up and does not allow the cool air in. This results in your system overheating which causes it to cycle off. Changing your air filter every 1-3 months, depending on conditions, will help prevent short-cycling and a number of other issues. This is the easiest and cheapest way to solve the AC short-cycling problem.
Low Refrigerant Level
This can be caused by either lack of AC maintenance or a leak in the system. Have your system checked for leaks and for proper refrigerant levels. This should be done when you have your system serviced (hopefully) before the cooling season starts. Even if you do have your system serviced regularly, leaks can develop due to corrosion, deteriorating seals and so on. These leaks need to be dealt with as soon as possible.
A Malfunctioning Thermostat
Short-cycling can be caused by a malfunctioning, mis-calibrated or improperly located thermostat. If it’s mis-calibrated, it’ll misread the temperature and cause the compressor to constantly cycle. If it’s malfunctioning, it’s not going to work even if it’s calibrated properly. If it’s incorrectly located, the correct temperature may not be read by the thermostat. Your HVAC provider can relocate it to a better location, preferably, a central location on an inside wall that’s not close to the return air register. This way, the thermostat won’t mistake the cool air for the output from your air conditioner.
If your compressor is failing, your AC system may short-cycle. Have your HVAC provider check the compressor for any signs of failure. If your compressor is an older unit, this could be the reason for the short-cycling issues. If necessary, have them replace the compressor and this should solve the short-cycling problem.
Wiring and Electrical Issues
Any number of electrical problems can cause short-cycling. Corroded wires, loose connections and so on, can cause your compressor to momentarily lose power and then cycle back on. Have your HVAC provider check the wiring in your AC system and repair or replace any bad wiring.
A Bad Low-Pressure Control Switch
If you’ve had everything checked and your system is still short-cycling, the low-pressure control switch might be defective. Have your HVAC provider check the switch and replace it if it’s not working.
The last possible cause of short-cycling could be that your AC system is too big for your home. If this is the case, it’ll overshoot the target temperature, shut off prematurely and then cycle back on when your house warms up. Have your HVAC provider check your system to see if it’s properly sized for your home. If it is, then there’s a different issue causing the short-cycling. If it is too large, then you’ll have to replace the AC system with a properly sized system.
How to Fix a Short Cycling AC Unit
If your air conditioner is short-cycling, try replacing the air filter. If you do that and it continues to short-cycle, call Mark Lindsay and Son Plumbing & Heating and we’ll set up an appointment for one of our skilled technicians to visit your home and examine your air conditioning system. They’ll diagnose and fix the problem so your system works properly and your family stays cool!