Is My AC Temperature Too Low At 65°?
If you set your AC temp too low, below 70°F (21.1°C), you risk icing up the indoor air conditioning coil, which will block the airflow through the ductwork.
Why is that? Because 70°F to 75°F is the optimal temperature range that engineers designed the equipment to operate within.
But, BIG BUT HERE, yours could still work at temperatures below 70°F.
Why? Not all homes or businesses are the same as you compare insulation, equipment size compared to square footage, humidity, duct work (airflow), area of the country, and on and on.
Design Tolerances For Air Conditioners
These are the temperatures that engineers build into AC equipment and it’s the same for heat pumps:
- Minimum: 70°F (21.1°C)
- Optimal: 75°F (23.9°C)
- Maximum: 80°F (26.7°C)
What Engineers Considered When Designing AC Units
The biggest consideration was that you just can’t please everybody. The design temperatures above were chosen by manufacturers because:
- Help prevent coil freezing issues
- Allow for optimal system efficiency
- Provides effective humidity control
- Maintains reasonable temperature splits (something mostly technicians and engineers understand).
- Prevents excessive system strain
- Balances comfort with energy usage
There are basically three classifications of refrigeration: Air Conditioning, Refrigerators and Freezers. Think about what happens inside your refrigerator when you set the temperature too low.
I have a friend who sweats a lot. He sets his AC temp too low for me. He keeps his house like a refrigerator, much to the abuse of his wife.
The Science Behind Coil Freezing
Let me break down what’s actually happening when your AC coil freezes up. Your air conditioner works by absorbing heat from inside your home through the refrigerant in the evaporator coil. When you set the temperature extremely low, the refrigerant gets too cold too quickly.
The moisture in the air that passes over this super-chilled coil freezes instead of just condensing. Once ice starts forming, it acts as an insulator, making the coil even colder, which creates more ice in a nasty cycle.
Soon enough, you’ve got a block of ice where your coil should be, and hardly any air can pass through. Your system is now working overtime but producing less cooling – talk about inefficient!
Hidden Cost Of Having Your AC Temp Too Low
Beyond just the mechanical problems, there are serious financial consequences to cranking that thermostat way down:
- Your energy bill skyrockets – sometimes 5-8% higher for each degree below 75°F
- Components wear out faster, meaning more repair calls
- Compressor failure becomes more likely (that’s a $1,500+ repair, folks)
- Your system’s lifespan gets cut short by years
Signs Your AC Is Struggling With Low Temperature Settings
How can you see the tell tale signs of setting your AC temp too low? Watch for these warning signs:
- Visible Ice Formations. You can see ice on the copper lines near the indoor unit or even on the outdoor unit.
- Weak Airflow. When the air coming out of your vents is less than you remember can mean the coil is iced up or the filter is too dirty.
- System running constantly. The AC never seems to cycle off and it’s struggling to reach that low setting that it always used to reach.
So, What If 70°F Is Just Too Hot
There are mechanical devices that can compensate for lower indoor temperatures. Freeze stats and condenser fan cycling controls.
A freeze stat is a device with a temperature probe stuck into the indoor coil. It will shut off or cycle the compressor to keep the indoor coil from forming ice.
A condenser fan cycling control will cycle the fan in the outdoor unit. Essentially raising the temperature of the refrigerant in the system and allowing the air conditioner to run more efficiently in lower outdoor temperatures.
Finding Your Comfortable Middle Ground
Instead of pushing your AC temp too low or to it’ limits, try this instead:
- Use ceiling fans to create a wind-chill effect (feels 4°F cooler!)
- Dehumidify separately – drier air feels cooler at the same temperature
- Zone your home so only occupied areas get super-cooled
- Consider a mini-split system for problem areas or hot sleepers
To Sum It Up:
There are those out there who think the lower they set their thermostat, the faster it will get cold. To them I say good luck and don’t set your ac temp too low
