Learn all about AC cycles in our guide. We explain AC short cycling and how to spot it. We also highlight what you can do about cycling issues.
Air conditioner cycles can be a great measurement of just how efficiently your air conditioning system is running.
But what are AC cycles? How often should air conditioners cycle? Is short cycling harmful?
We tackle these questions and more in our latest home cooling guide.
What are AC Cycles?
An AC cycle is the time the AC unit is running to cool your home.
To cool your home in the most efficient manner the thermostat function should be used. This means your AC unit will automatically engage when a set temperature threshold is reached, in order to cool your home.
When it starts running, this is the start of the cycle. When the desired temperature is reached, the AC will go into "sleep mode" again and the cycle ends.
If you're not using the thermostat and your AC is endlessly running (we don't recommend you do this in the summer) then cycles don't apply.
How Often Should my AC Cycle?
A healthy air conditioner that is well suited to its environment in terms of cooling capacity (remember to size your AC unit according to your room) should cycle for approximately 20 minutes, give or take a few minutes.
That means an AC cycle rate of about 3 times per hour is optimal. But, getting 2 or 4 cycles per hour is also pretty good.
Really high temperatures will cause the cycle length to be longer as there is such a big difference between the thermostat setting and the actual room temperature. Therefore, your AC unit has more work to do.
Air conditioners that dehumidify will also take longer to complete cycles as dehumidifying takes a lot of work in certain areas.
AC Cycling Issues
Both short cycling and long cycling can represent big problems with your air conditioner.
Let's take a look at the causes and possible fixes.
Short cycling is one of the most common problems with air conditioners. Sometimes it can be fixed with just a few minor adjustments but otherwise you'll need professional help from an HVAC technician.
It's a problem that should never be ignored as the consequences of this can be expensive in the form of a new replacement AC system.
What Exactly is AC Short Cycling?
Short cycling is what those in the HVAC profession call a heat pump or air conditioner that is stuck in the start cycle. It never manages to complete a full cooling cycle and can turn off and on very quickly.
An air conditioner usually runs until the thermostat temperature is met. It then powers down the compressor and goes into standby mode.
However, when an air conditioner is short-cycling the compressor stops before the cooling cycle is fully completed. This puts pressure on the compressor as it needs to work harder than it is designed for.
What Causes Air Conditioner Short Cycling?
There are numerous reasons that an AC system is short cycling. They range from the simple and inexpensive to fix, to problems that will require professional help.
You can obviously troubleshoot the simple causes yourself before calling help. We'll start with the simplest cause.
- The air filter needs cleaned - a clogged filter is easily cleaned. This should be part of your regular AC maintenance and should be done at least every 3 months.
- The AC unit is not a good fit for the room (either too big or too small) - unfortunately this means replacing your AC system if you want it to run at full efficiency.
- The thermostat is faulty/miscalibrated - Contact an HVAC technician.
- Air leak in the ventilation - Contact an HVAC technician.
- Refrigerant is leaking - Contact an HVAC technician.
Expensive Consequences of Short Cycling AC
Short cycling is a problem that should never be ignored as it can lead to expensive consequences.
For starters, the compressor is put under unnecessary pressure as it needs to work harder than it is designed for. This can lead to overheating which will eventually cause it to break down.
Compressors are expensive and this is not something you want to have to replace. In some cases it may be easier to just replace the whole system
Secondly, the start up sequence of an air conditioner is the process that uses the most energy and therefore consumes the most electricity.
If your air conditioner is short cycling, it is repeatedly starting up and consuming large amounts of expensive electricity.
Overly long AC cycles are a symptom of underlying problems too. They can cause really expensive electricity bills if you don't get to the root of the problem and solve it.
Typically, a long cycle would be anything over 25 minutes.
What Causes Air Conditioner Long Cycling?
There are a few common causes of long cycling in AC systems. There are the two most probable causes.
- The filters are clogged and need cleaned.
- The refrigerant levels are low and the freon needs topped up.
- Your AC system is too small for your room - it is taking so long to complete a cycle because it struggles to cool the room and get the temperature down to the desired thermostat level.
- The ductwork is not sealed properly or is not the correct size.
- Extreme temperatures of above 100°F and high levels of humidity - weather conditions like this can be problematic for your AC to combat, leading to longer cycle times.
An ideal cycle time of around 20 minutes is what an efficient AC cooling system should be achieving (give or take a few minutes).
An AC short cycling or even long cycling is something that should be looked into as soon as possible.
The problem could be something as small as clogged filters but there's always the chance it might be something more serious and expensive to fix.
Consult an experienced HVAC technician if you're concerned and get to the root of the problem before it causes your compressor to overheat and fail.