What is AC Short Cycling and Why Is It a Problem?

Let’s begin by understanding what exactly AC short cycling is, and how it affects the functioning of your HVAC system. This is one of the most frequently occurring problems homeowners face with their heating & cooling units. Short cycling refers to a technical/electrical fault where a heating or cooling cycle finishes abruptly before its stipulated time. A normal cycle for an HVAC system usually lasts anything between 20-30 minutes.

When an AC or a heating system starts, it is the beginning of a cycle, and when it shuts off, it is the end of a cycle.

This abnormal tripping or cutting of a cycle results in higher energy bills, as well as shortening of the lifespan of the HVAC system. When you notice your AC unit is not able to function at its peak level and cuts off before finishing a cycle, call an expert in AC repair. The same applies to a heating system where the furnace is unable to complete its full heating cycle.

This air conditioning short cycling problem doesn’t go away so easily, as there might be an issue with the compressor or thermostat which trips frequently. If the cycle time is too short, it means there’s a fault with the circuit of the heating & cooling system. From a layman’s point of view, it is a situation where the AC unit doesn’t get the chance to blend fully with the existing air temperature inside a residence. Let’s find out the causes.

What are the Causes of HVAC Short Cycling?

There can be a myriad of reasons depending upon the severity of the issue. It can be a clogged air filter, refrigerant leak, or defect in the thermostat. This automatically results in short cycles for your HVAC system, without achieving the desired comfort goals. Here are some of the main reasons for air conditioner short cycling which you need to know.

Clogged Air Filters

When you perform regular cleaning and dusting of your house, the small dust particles find their way into the air filter. If the AC air filter is not cleaned regularly, the debris and dust in the system will reduce its capability. Usually, the air filter gets clogged with kitchen smoke, skin flakes, dust, dirt and other suspended particulate matter.

As your HVAC air filter gets old, it collects excess dust and debris, which means that your system has to work harder for heating or cooling a small space. This results in shorter cycles, system overheating, cutting off, and tripping. Almost all air conditioner manufacturers suggest changing the air filter every 5-6 months to enjoy optimal heating & cooling.

Refrigerant Leak

The leaking of refrigerant can result in severe problems like AC short cycling or shutting down the system. When there’s a leak in the refrigeration line, the fluid present in the system is unable to trigger a chemical reaction, thus preventing pressurization. The low refrigerant level can harm the compressor.

The chemical in the refrigerant plays its part in the cooling process. When there’s a leak in the ductwork, pipe, and lines, the system needs to work harder to achieve the desired cooling. You cannot solve this problem in a DIY manner.

Improperly Sized Units

When your HVAC system is not according to the size of your room, it results in brief cycles. This is because when a unit is too small compared to the space in your house, it has to work harder to cool or heat the living area. Similarly, when a system is oversized, it will heat and cool a space too quickly, cutting off before reaching the ideal temperature.

Thermostat Issues

If your thermostat is improperly calibrated or it is an older analog version, it may find it difficult to gauge the room temperature. This can result in your AC unit switching on & off randomly. Even though the system starts effortlessly, the thermostat may abruptly shut down, thinking it has achieved its desired goal.

Another common problem is the poorly placed AC unit at home, especially in corners and near the food preparation areas, which usually results in inaccurate readings. If the thermostat is installed in a place where it receives direct sunlight, it can show faulty or deceptive readings. This is the reason why the cooling system turns on & off frequently.

Electrical Issues

Electrical issues can be the main cause of AC short cycling for all kinds of heating & cooling systems. If there’s a fault with the electrical unit or circuit, it can cause the air conditioner to abruptly shut down in the middle of a cooling cycle. This is without reaching the desired temperature. When the wires become loose, or the circuit board, switches & resistances are corroded, it may cause HVAC short cycling issues.

When you encounter such electrical issues with your air conditioning unit, it is best advised to call an HVAC technician, instead of trying to solve it by yourself. It can be risky.

Frozen Evaporator Coil

Another common reason for air conditioner short cycling is the freezing of the evaporator coil. When the AC compressor moves the cold refrigerant into this coil, the heat is removed, and cool air is circulated throughout the room. But when your AC unit has a frozen evaporator coil, it can cause the system to overheat, which results in short cycling.

When you notice that your air conditioning system has a frozen evaporator coil, try fixing it by yourself, by completely switching off the AC unit for 24 hours. This can help the coil to defrost, melting away all the ice. If this doesn’t work, call an HVAC professional.

Single-Stage Systems

Short cycling or brief periods are common with single-stage systems, as the air is not able to blend properly with an existing room temperature. The characteristics of a single-stage air conditioning system are that it cools down fast and shuts off. This air isn’t mixed properly. So, the hot rooms stay hot, and the cold places stay cold. Again after 2-3 minutes, the thermostat turns on, blasting cold or hot air, before turning off.

Leaking Ductwork

If the ductwork of your HVAC system is leaking, it can cause an imbalance in the air pressure that is being pumped out from the compressor. This air pressure imbalance can be one of the causes of short cooling & heating cycles. Here, the compressor is forced to turn on & off more frequently. The best way to fix the problem is to find the leak and seal it with adhesive tape or sealant.

If you’re not able to fix it by yourself, call an expert in AC repair in Garland or wherever you live in Texas. They have the specialized tools and know-how to seal all kinds of leakages in HVAC ducts.

Clogged Drain

As and when the air conditioner runs daily, it normally collects moisture, which needs to be drained out from the AC unit. If the drain is clogged, the moisture can build up, resulting in a frozen evaporator coil. This is one of the reasons for short cycles.

An expert AC technician can check for any clog in the drainage pipe or line, by disconnecting it from the main system. If there is a blockage due to accumulated debris, they’ll clear all the unwanted stuff, and restore the line.

Defective Relay Switch

The flow of the current to the compressor is controlled by the relay switch located inside the HVAC system. If the switch is faulty, it may cause short cycles due to inadvertent turning on & off of the compressor. It is best suggested to replace the faulty relay switch with a new one.

These were some of the main reasons for AC short cycling that homeowners face. Such issues can be avoided through regular maintenance and periodic overhauls. Therefore, you need to contact a certified and accredited AC repair service in Forney, or wherever you live in Texas, like Copeland Homeland Services who can identify the problem, and offer a credible solution. This is how you’re able to keep your HVAC system in a running condition throughout the year.

By Copeland Home Services June 25, 2024

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