08/07/2026
📢 We get a lot of calls during these heat waves from customers concerned their system isn't working when it is working it just is struggling in this heat (like the rest of 🥵). This article does a great job of explaining it from the mechanical perspective.
Our recommendations to help during these times:
- Maintenance: whether done by you or more thoroughly by a company; at a minimum your filter needs to be clean, and your outside unit *gently* hosed off.
- Keep your thermostat set at one temperature - DO NOT RAISE IT DURING THE DAY. If you allow your space to get hot and then attempt to cool it down, your system will run constantly trying to reach the desired temp. It isn't more efficient and your house will be HOT.
- Close blinds and curtains to block the sun and help keep the heat out.
- Check your insulation and windows if it is a major problem, look at other options to keep the heat out.
https://www.npr.org/2023/07/19/1188328688/heat-wave-air-conditioner-tips
From the article: "Under these conditions, "your efficiency drops and you actually lose a little capacity, which means the unit is going to run non-stop," according to James Barry, who owns Doctor Cool & Professor Heat, a company in League City, a suburb of Houston.
All air conditioners work the same
Garimella (mechanical engineer) explains that all air conditioners work on the same basic principle — a cold, low-pressure refrigerant evaporates and absorbs heat from a room and then is compressed before condensing and releasing the heat by way of an outdoor heat exchanger. The refrigerant is then recycled in a closed loop.
He compares the energy required to do this to climbing a mountain. The hotter the outdoor temperature, the more effort (and energy) needed to make the climb. "So, the higher the ambient temperature, the more the compressor has to work, the more electricity [is] needed, and the problem just keeps getting compounded," he says.
Compressors work less efficiently at higher heat, which means they need more power to do the job. Higher humidity also places "a humongous additional load" on an air conditioning system, he says.
Simply installing a bigger air conditioner might sound like a solution to the problem. Not so, according to Reinhard Radermacher, a professor of mechanical engineering at the University of Maryland.
It may be fine on the hottest days, but "if 90% of the time [an air conditioner] is oversized," it's not efficient, he says."
Extreme temperatures present a significant challenge to AC systems, which engineers and installers say are really only designed to keep indoor temperatures about 20 degrees cooler than outside.