With summer temperatures in Glendale often well over 100 degrees Fahrenheit and sometimes pushing 120 degrees, you depend on your home’s air conditioner for safety as much as comfort. With temperatures consistently this high, it’s important to know if the outdoor temperature will affect your system’s performance. Use this guide to learn how your AC unit works, four ways that high outside temperatures affect its performance, and what you can do to reduce those effects.
Understanding How Your AC Cools Your Home
Your air conditioner works based on the second law of thermodynamics, which states that heat transfers from where it’s hotter to where it’s cooler. In your air conditioner, the refrigerant is the medium through which heat transfers. As the refrigerant moves through the coil inside of your house, the pressure drops, causing it to expand quickly and get cool. This instantly starts transferring the heat from the warm air moving through the system to the cool refrigerant.
When the refrigerant moves to the outside unit, the compressor forces it into a higher pressure state in the condensing coil. As you increase the refrigerant’s pressure, its temperature increases so that it’s warmer than the air outside, forcing the heat to transfer to the cooler air. When the outside temperature starts approaching the temperature of the refrigerant, the amount of heat transferring to the air slows down, affecting your system’s performance.
The normal operating range for an air conditioner is 60 degrees to 100 degrees Fahrenheit. Here’s what happens to the system’s ability to expel heat outside as the temperature increases.
- 110 degrees: starts having small problems
- 120 degrees: struggles to expel heat
- 130 degrees: will have noticeable problems
- 140 degrees: will have serious problems
- 150 degrees: can barely expel heat
Remember that you’re concerned with more than just the ambient air temperature. Rather, you have also to consider the solar heating of your unit if the sun is shining down on it during the heat of the day. On a day when the temperature is 110 degrees, a coil in the sun could be as much as 160 degrees, making it closer to the refrigerant’s temperature.
The following are four ways high outside temperatures can affect your AC unit’s performance.
1. Higher Costs of Cooling
The second law of thermodynamics mentioned earlier also indicates that more heat will transfer when there’s a greater difference in temperature between the heat source and the heat target. Conversely, the closer that temperature is, the less heat will transfer.
Your system’s SEER rating is based on operating at 95 degrees Fahrenheit, with the system’s refrigerant achieving about 200 degrees. As the temperature rises above that point, your unit’s efficiency will decrease because it can’t expel as much heat as quickly, especially above 100 degrees. With normal summer temperatures around Glendale, you may see a decrease in your system’s efficiency by as much as 30% if your outside unit is shaded. Let your unit get above 140 degrees, and you’ll see it drop 50% or more, doubling your cooling costs.
2. Lower Cooling Capacity
One of the major factors that influence your decision when purchasing an air conditioner is its cooling capacity. That capacity is represented in British Thermal Units (BTU), or tons. Both ratings look at how much heat the system can transfer per hour. However, that rating is based on operating under normal conditions. Once the temperature outside exceeds 100 degrees, the unit is no longer operating under normal conditions. Rather, a 3-ton unit may only provide the capacity of a 2-ton system when temperatures hit their peak.
With reduced cooling capacity, your system will run longer cooling cycles without reducing the temperature as much. Most air conditioners will max out at cooling your air to about 15-20 degrees cooler than the air outside. If the temp outside is 100 degrees, your unit will struggle to keep the temperature in your home consistent at 80 degrees. The hotter it gets outside, the less temperature difference your AC unit will provide.
3. Inconsistent Indoor Temperatures
You’ll find that on exceptionally hot days, your indoor temperature will swing, regardless of the temperature you have set on the thermostat. If you keep your thermostat set at 78 degrees, for example, days that exceed 110 degrees may see your indoor temperature hover in the mid-80s. Some people think this signifies an issue with the air conditioner, but it’s simply the limits of how the system works. You can ease this by adjusting your AC unit’s programs to increase a few degrees during the hottest parts of the day and then bring the temp back down during the cooler times overnight.
4. Shorter AC Lifespan
The national average lifespan for a central air conditioner is 10 to 15 years, with annual HVAC maintenance. However, as the strain on the system increases, components will wear out more quickly, shortening that lifespan. The reduced efficiency that comes with higher temperatures increases the strain the unit experiences while it runs.
In Arizona, it’s more common for central air conditioners and heat pumps to last closer to the 10-year mark than 15 years or beyond. The component that experiences the most strain due to the heat is the unit’s compressor. In most cases, you’ll replace the entire unit once the compressor fails. Fortunately, there are some things you can do to help reduce the effects of the summer heat and extend your equipment’s service life.
Ways to Reduce the Effect of High Heat
Start by finding a way to provide some shade for your outdoor unit. Whether using vegetation or constructing a shade structure, give plenty of room for the air to circulate. The recommended clearance is 2 feet around all sides of the unit and 5 feet above it. Most days, stay within a safe range for your AC unit to continue working well when you take away the solar heating effect, so this is a critical step.
Next, make sure that you’re staying current on your maintenance. Among other things, a technician will clean your system to ensure it can circulate air properly, which affects how the system transfers heat. They’ll also check to make sure there’s optimal refrigerant charge in the system. Low refrigerant inhibits proper system pressure, which reduces its ability to absorb and release heat.
Finally, set your temperature inside a little higher. When it’s over 100 degrees outside, 80 degrees in your home still feels cool. Setting your temperature lower only keeps your system running longer, further straining your air conditioner and increasing the risk of it breaking down and needing an AC repair. Use your ceiling fans to make the air feel a few degrees cooler when the thermostat is set to a higher temperature to reduce the strain on your AC unit. Make sure the fan is rotating in the counterclockwise direction to get the full windchill effect.
Homeowners throughout Glendale have trusted Christian Brothers Air Conditioning Plumbing Electrical to help beat the heat since 1976. Our award-winning team provides heating and air conditioning maintenance, repair, and installation. We can also help you with indoor air quality, insulation, and a full complement of residential electrical and plumbing services. Call us today to schedule AC maintenance with one of our NATE-certified technicians to help reduce the strain on your air conditioner this summer.
