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10 Mar 2023

Author: Jeff O'Hara

You know that your air conditioner is working. You can feel the cool air blowing from the vents and you can hear the outdoor compressor fan whirring away. Still, for some reason, your AC never seems to get cool enough in the house, or it always feels too humid to be comfortable. 

The same scenario can also apply to your furnace, with it operating correctly, but it always comes up a little bit shy of keeping your come toasty in the winter. 

Your AC’s Problem Could be Short Cycling. 

Short cycling occurs when whichever half of the HVAC system you’re using runs for extremely brief periods, over and over, while never quite achieving its comfort goal. It’s a frustrating situation for your family, and it could be a costly concern, raising gas and electric bills and the looming threat of expensive AC repairs soon. 

The period from when your furnace or air conditioner is activated to run by the thermostat until the set temperature is reached and the system turns off is called a “cycle.” Regular cycles for an HVAC system should last between 20 and 30 minutes, particularly on hotter –or colder—days, depending on the season. The time between heating or cooling cycles will vary from home to home based on several factors, but in a well-insulated home, the 20 – 30 minute average should apply.  

The start of a cycle is when your HVAC system is working at its hardest and its components are under the most stress. Each time your air conditioner kicks in, the compressor motor is taken from idle to 1,000 revolutions per minute. Instantly. The power required to energize the compressor motor and pressurize the refrigerant lines several times an hour exceeds what your AC system would use running all day and night. 

Short Cycling is Bad, But It Doesn’t Spell the End of Your HVAC System! 

Constant on-and-off power cycling significantly strains your heating and air conditioning systems, but there is usually a cause and a cure for the issue. The first thing the homeowner needs to do is confirm that their HVAC system is, in fact, short-cycling. 

How Can I Tell If My HVAC is Short-Cycling?

Though your HVAC system may be loud, its noise blends into the background with the other normal sounds you hear each day. Unless you’re an air conditioning technician, you may not notice that your HVAC system is short-cycling until you investigate mysteriously higher energy bills or detect a noticeable decrease in system performance. 

Why Does an HVAC System Short Cycle? 

Several causes can make your system short cycle by themselves –or in combination with each other. 

Dirty Air Filters

When it comes to homeowners taking care of regular maintenance tasks, lawns get mowed, houses get power washed, and maybe even a fresh coat of paint on the trim. While all this is happening, your HVAC system’s air filter is becoming increasingly clogged with dirt, dust, skin flakes, cooking smoke, pet odors, and all sorts of horrible stuff. The older your HVAC air filter is, the more crud it will have collected, which means your system must work much harder to draw air into the system to be heated or cooled. 

Air conditioning companies recommend changing your HVAC system filter no less than every 3 – 6 months. If you have smokers in your home or more cooking smoke than the average home, you may want to change your air filter every month. 

Low Refrigerant/Refrigerant Leak

The liquid refrigerant in your HVAC system requires highly pressurizing the fluid to trigger the chemical reaction needed to draw heat from your home. When there is a leak in the refrigerant lines, air and refrigerant can escape from the line, preventing complete pressurization.

The refrigerant circulation system of your AC unit is a “closed loop” system, and under normal circumstances, your AC should never require a “coolant charge.” Topping off the Puron level in your system may briefly alleviate the problem, but you’ll be in the same situation again down the road. Loss of refrigerant in an AC system is always due to a leak. The sooner you locate and repair the source, you’ll improve not only the performance of your AC unit but your monthly energy bills as well.

Thermostat Issues

Older thermostats become less accurate over time, especially if you still have an older analog thermostat. If setting your desired room temperature involves turning a dial or sliding a level, you have an analog thermostat. Join the twenty-first century and install a more accurate and reliable digital thermostat, or go all-in with a wi-fi enabled programmable model. 

Another common problem with thermostats is where they are placed in the home. Corners are a troublesome area for thermostats, as drafts are more common and can result in inaccurate readings. Near the kitchen is another poor idea for a thermostat location, as the heat generated by cooking can cause your AC to come on while the rest of the house is cool. 

Leaking Air Ducts

Most ductwork currently installed in Houston area homes is made of an internal metal coil that acts as a frame, around which an air-tight insulated plastic wrap is placed. HVAC ductwork is subjected to extreme temperatures when installed in attics, and interior walls, which leads to the outer wrap breaking down over time. Cracks in your ductwork covering allow untreated air from outside the HVAC system to enter your home, forcing your AC system to work harder to achieve the desired temperature. 

What Can I Do to Prevent AC Short Cycling?

Set realistic goals with your thermostat. Central heating and air conditioning systems are amazing appliances that allow our families to enjoy in-home comfort, regardless of the weather. One significant problem folks face, particularly in the summer months, is asking more of our air conditioners than they can deliver. 

During the hottest summer days, your air conditioner should be able to deliver indoor temperatures around 25 degrees cooler than outside. Setting your thermostat’s temperature accordingly will help prevent the freezing of your evaporator coil and cut down on the number of short cycling events. If it’s 95° outside, cut your air conditioner a little slack and set the thermostat for 72 or 74°. 

How Can Nick’s Air Conditioning Help with AC Short Cycling?

Regular Maintenance

Book an HVAC maintenance service call, where our licensed and experienced professionals will perform a 32-point inspection of your air conditioning system and a 20-point check of your furnace and heat exchanger. They’ll investigate any potential problems that could be causing your short-cycling issues and make recommendations on the best course of action. 

Check Low-Pressure Control Switch

While air conditioner short-cycling is a common HVAC problem, the low-pressure control switch often gets overlooked. The purpose of the switch is to detect excessive pressure in the compressor and cycle the compressor off, allowing the evaporator coil to defrost. 

Relocate Thermostat

If it is determined that your thermostat is in a poor location to measure the temperature correctly and is causing your short cycling, a Nick’s HVAC specialist will suggest relocating your thermostat. The optimal site for homes that rely on a single thermostat will be an open room, like a living or dining room. 

Call Nick’s if Your AC or Furnace May be Short-Cycling.

Get in front of a short-cycling HVAC issue before it has a chance to do long-term, expensive damage to your furnace or AC unit. Let one of our HVAC experts confirm your issue is indeed short-cycling and determine what Nick’s needs to do to get your HVAC system back to normal operation. 

Call Nick’s Today; We’re on the Way!

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