Surviving the Heat: A Guide to Your Cooling System
When an Illinois summer hits its peak, we rely on our air conditioning more than ever. But when extreme heat waves roll through Frankfort, you might notice your home or business isn't getting as cold as your thermostat setting. Before you assume your system is broken, it’s important to understand how air conditioners are designed […]
When an Illinois summer hits its peak, we rely on our air conditioning more than ever. But when extreme heat waves roll through Frankfort, you might notice your home or business isn't getting as cold as your thermostat setting.
Before you assume your system is broken, it’s important to understand how air conditioners are designed to handle extreme weather. At Climate Control Systems, we want our customers to know what to expect and how to protect their equipment when the temperatures soar.
The "20-Degree Drop" Rule Explained
If it is 100°F outside and your thermostat is set to 70°F, you might notice the indoor temperature stubbornly hovering at 78°F or 80°F. In most cases, your system is working exactly as it should.
This is due to the 20-Degree Rule, an HVAC industry guideline stating that air conditioning systems are designed to reliably maintain an indoor temperature about 20 degrees cooler than the outdoor temperature.
Why is there a limit?
Air conditioners don't cool your home to a specific number; they remove a set amount of heat per hour. Your system's sizing is calculated based on average regional temperatures, not record-breaking heat waves. Pushing a system to cool 30 degrees below the outdoor temperature requires far more capacity than standard equipment possesses.
Outdoor Temperature
Realistic Indoor Expectation
85°F
68°F – 70°F
90°F
70°F – 72°F
95°F
75°F
100°F+
78°F – 80°F
(Note: High humidity will make the system work even harder, as it must remove moisture from the air before it can effectively lower the temperature.)
What Happens if You Lower the Thermostat Anyway?
It’s tempting to drop the thermostat to 65°F during a heat wave to make the house cool down faster, but air conditioners do not work that way.
Setting the temperature significantly below what the system can achieve will not speed up the cooling process. Instead, it causes the compressor to run continuously. This nonstop operation leads to:
Excessive wear and tear on vital components.
Spikes in utility bills.
Frozen evaporator coils, which will stop the system from cooling entirely.
4 Ways to Help Your AC Keep Up
When a heat wave hits, you can take some pressure off your system to keep your home or business comfortable:
Set Realistic Goals: Aim for a thermostat setting 20 degrees below the outdoor temperature.
Change Your Filter: A clogged, dirty air filter restricts airflow, forcing your system to work much harder and increasing the risk of a frozen coil.
Block the Sun: Close blinds, curtains, and shades during the hottest parts of the day to prevent solar heat gain from fighting against your AC.
Clear the Condenser: Ensure the outdoor unit is free of weeds, leaves, or debris so it can efficiently exhaust the heat it pulls from your building.
When to Call for Service
While a 20-degree differential is normal, you should reach out to us if:
Your indoor temperature is drastically more than 20 degrees warmer than outside.
The system is blowing warm air.
You notice ice building up on the indoor or outdoor coils.
The system is making unusual grinding, squealing, or banging noises.
Brought to you by Climate Control Systems — keeping your family and business comfortable all year long
