Mini Split Turning On And Off ( 4 Causes And How To Fix)

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If your air conditioner keeps cycling on and off, you’re experiencing what’s known as short cycling. The good news is that you’re not alone. Short cycling is one of the most common air conditioner problems.

Unfortunately, it’s also a problematic issue. If you don’t fix it immediately, you may soon have to replace the air conditioner.

What’s Short Cycling?

As the name suggests, short-cycling occurs when something prevents the AC from completing a full cooling cycle.

A complete cooling cycle occurs from the moment the unit kicks on to when it reaches the temperature set on the thermostat, at which point it kicks off again.

On a moderately hot day, most air conditioners will cycle about three times per hour. Each full cycle lasts about 10 minutes. Then the AC stops for about 10 minutes before going through another cooling cycle.

Short cooling cycles are shorter than the conventional 10 minutes. It can be as short as 5 minutes in some cases.

The Consequences of Short Cycling

Short cycling is often a symptom of an underlying problem. However, it can also cause further problems. The following are a few ways short cycling can be bad for you and your AC;

Higher power bill

An air conditioner uses the most power when it’s starting. Some studies show that the AC can draw up to 5X more power when starting than when running. It follows, therefore, that you’re likely to end up with a massive power bill if your AC is trapped in a continual startup process.

Faster wear and tear

The constant startup can also cause the compressor to wear faster. That’s because there’s greater friction when the unit is starting up and when it’s stopping. Accelerated wear and tear may necessitate frequent (and costly) repairs and parts replacement.

Compressor burnout

If the issue isn’t resolved early, you risk burning out the compressor. This can be a costly loss because the compressor is the most expensive part of the air conditioner. Replacing an AC compressor typically costs more than half the total cost of a new AC plus relevant accessories.

Most AC warranties don’t cover short cycling

The worst part of it all is that the manufacturer will, in most cases, not shoulder any blame in case of AC short cycling. Why? Because short cycling is considered a consequence of poor maintenance. So, you can forget about the manufacturer covering the cost of repairs or replacements.

4 Reasons Your Mini Split Keeps Turning On and Off & How to Fix It

Fortunately, most AC issues that cause AC cycling are well known and easy to prevent. They include the following;

1. An oversized air conditioner

Let’s begin with a mistake most people make, albeit unknowingly. An air conditioner that’s too large for the application will undoubtedly result in short cycling.

Why? Because a large AC in a small room reaches the set temperature faster. Remember that cooling is all about lowering the temperature of a fixed volume of air. If the air volume is small, as is the case in a small room, a large AC may lower the room’s temperature to the thermostat setting in 5-7 minutes.

Solution: Buy the right size air conditioner. Generally, you need about 20 BTUs per square foot. However, you may want to consult an HVAC professional.

2. The thermostat’s location

Short cycling may also be a consequence of the wrong thermostat location. This is especially true if the thermostat is located too close to a supply vent.

The thermostat’s sensor bases its instructions on the air immediately surrounding the unit. As a result, if the thermostat occasionally experiences a cool breeze originating from the vents, it may “wrongly” interpret it as a sign that the entire home is cool enough and thus turn off the AC.  

Solution: The only solution here is to find a centralized position for the thermostat. The air around the AC must be an accurate representation of the air throughout the home/room.

3. A refrigerant leak

Your AC uses refrigerant (or freon) that flows through the system, collecting heat from air handlers and dumping it outside during cooling. The process is reversed during heating (for heat pumps). When there’s a leak, the AC will detect low pressure, making it challenging to achieve optimal operation. Refrigerant leaks are also bad for your health.

Most air conditioners are designed to shut off as soon as low refrigerant pressure is shut off to avert further problems. However, while the AC is off, pressure naturally rises, often triggering the AC to restart. This on-off cycling can continue for ages.

Solution: Call a licensed HVAC technician immediately. You must never handle refrigerant leaks yourself unless you’re a licensed technician. It’s even legally prohibited in some states.

4. A dirty AC filter

Finally, short cycling may also be a consequence of a dirty air conditioner filter. A dirty AC filter restricts (and can even block) airflow through the air conditioner.

If the problem isn’t fixed promptly, airflow restriction can leave the evaporator coil with insufficient heat to absorb. The coil depends on the heat to keep the refrigerant in liquid form. Therefore, if there’s no heat, it may freeze.

A frozen evaporator coil is characterized by decreased cooling capacity, indoor water leaks, and, yes, an overworked compressor that keeps turning on and off.

Solution: The first solution is to ensure proper maintenance. Clean the filter as the manufacturer recommends and change them at least once per cooling season or more frequently as the manufacturer recommends. If you already have frozen evaporator coils, call a licensed technician.

Now You Know

It’s almost impossible to achieve the desired comfort levels when the air conditioner is short cycling. Even in the short (and rare) periods when it keeps the room cool, the constant start-stop cycle can be too noisy to bear. Even worse, short cycling can damage your AC without warning.

So, you must address the issue as soon as you find out. If you can’t pinpoint the cause, call a licensed HVAC technician immediately.

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