Why Is My AC Short Cycling?

Your AC cannot make up its mind.

One minute, it runs. Then it stops. Then it runs again.

If this story sounds familiar, you’re not alone. This frustrating AC behavior, known as “short cycling,” is a common problem for homeowners in Mount Pleasant, and across Wisconsin. Consider it a red flag waving vigorously, signaling that something isn’t quite right with your air conditioning system.

Ignoring it can lead to higher energy bills, a less comfortable home, and potentially expensive repairs down the line. First Call Heating & Cooling, Inc. can help. Many causes of short cycling are fixable, and understanding why it happens is the first step to getting your cool back.

What Exactly is AC Short Cycling?

Imagine your air conditioner as a marathon runner. Ideally, it should start, maintain a steady pace for a good stretch, and then cross the finish line before taking a well-deserved break.

Short cycling is like a runner sprinting for 100 yards, stopping, sprinting again for another 100 yards, and so on.

Instead of completing a full, steady cooling cycle, your AC unit turns on, runs for a very brief period (often less than 10-15 minutes), and then shuts off, only to turn back on again shortly after. This constant stopping and starting is inefficient and puts undue stress on your system.

The result?

Your Mount Pleasant, home might never truly feel cool or properly dehumidified, and your AC is working harder (and costing you more) for less effective results.

Why Your AC Might Be Short Cycling

Short cycling can be triggered by a variety of issues, ranging from simple maintenance oversights to more serious mechanical problems. Here are some of the most common reasons your AC might be acting up:

1. Your HVAC Filter Is Clogged

This is perhaps the most common and easiest issue to fix. A dirty, clogged air filter acts like a suffocating blanket for your AC system. It restricts airflow, making your unit work harder to pull air in. This increased strain can cause the system to overheat and shut off prematurely as a safety measure.

Regularly checking and replacing your air filter (at least every 1-3 months) is crucial for optimal AC performance and preventing short cycling.

2. You Have Thermostat Troubles

Your thermostat is the command center of your AC system. If it’s malfunctioning, installed in the wrong spot, or has dead batteries, it can send incorrect signals to your air conditioner, causing it to turn on and off erratically.

Placing a thermostat too close to a heat source (like a sunny window or a heat-generating appliance) can lead it to believe your home is hotter than it actually is, triggering short cycles. Locate your thermostat on an interior wall, away from direct sunlight or drafts.

3. Your AC Has Low Refrigerant Levels

Refrigerant is the lifeblood of your AC system, responsible for absorbing heat from your home and releasing it outside. If your system is low on refrigerant, often due to a leak, it struggles to cool your home effectively. Low refrigerant levels can lead to your AC running constantly without achieving the set temperature, eventually overheating, and shutting down.

Low refrigerant can also cause ice to build up on the evaporator coil, further hindering performance and leading to frequent cycling. Refrigerant leaks require professional attention, as handling refrigerants can be hazardous.

4. You Have an Oversized AC System

It might seem counterintuitive, but an air conditioner that’s too large for your home can cause short cycling. An oversized unit will cool your home too quickly, reaching the thermostat’s set temperature before it’s had enough time to properly dehumidify the air or circulate it throughout your space.

This issue results in the unit shutting off prematurely, only to turn back on again as soon as the temperature ticks up slightly. This constant on-off cycle is inefficient and doesn’t provide consistent comfort. Plus, it puts undue stress on your compressor.

5. Your Home Has Electrical Issues

Faulty wiring, a damaged control board, or worn-out electrical components like capacitors and contactors can disrupt the normal operation of your AC system. These electrical glitches can cause the unit to start and stop intermittently, leading to short cycling. Diagnosing and fixing electrical issues requires the expertise of a trained professional.

6. Your Evaporator Coil is Frozen

Restricted airflow (from a dirty filter or blocked vents) or low refrigerant can cause the evaporator coil to freeze. When this happens, the system shuts down until it thaws—and then restarts, often repeating the cycle. This cycle of freezing and thawing leads to frequent short cycling.

How to Fix AC Short Cycling

Some causes of short cycling can be resolved with a simple DIY fix, while others demand professional attention.

Here’s a step-by-step approach:

1. Check and Replace Your Air Filter: This is always the first and easiest step. If your filter is dirty or clogged, replace it with a clean one. This simple act can often resolve short cycling and improve overall airflow.
2. Inspect Your Thermostat: Ensure your thermostat batteries are fresh and that it’s positioned correctly, away from heat sources or direct sunlight. Check the settings to make sure they haven’t been inadvertently changed.
3. Clear Vents and Registers: Take a walk around your home and ensure that no furniture, curtains, rugs, or other obstructions are blocking your supply or return air vents. Restricted airflow can contribute to coil freezing and short cycling.
4. Schedule a Professional Inspection: If you’ve tried the basic troubleshooting steps and your AC is still short cycling, it’s time to call in the experts at First Call Heating & Cooling, Inc. Our licensed HVAC technicians will check the refrigerant level, electrical connections, evaporator coils, and other possible issues. We can also test the system controls and calibrate your thermostat.

Don’t Wait for a Heat Wave!

Short cycling may seem like a minor problem, but it can cause other problems for your AC that could lead to costly repairs. Not to mention, you aren’t getting the comfort you deserve.

Don’t ignore it. If your AC is short cycling, addressing it quickly ensures your system is running efficiently before the peak heat hits in July and August. For a free HVAC consultation, call First Call Heating & Cooling, Inc. at 262-320-8635 or request service online.