Why Can’t I Cool My House?

Mar 11

It’s the middle of summer. Your thermostat is set to 70°F, but your home refuses to cool below 78°F. Why does this happen?

There are several possible reasons, but let’s look at the most common issues and solutions.

The 20-Degree Myth

You may have heard this before:

“If your HVAC system can cool your home to within 20 degrees of the outdoor temperature, it’s doing all it can.”

Here’s the truth: this theory is not taught in any HVAC trade school — ever. It’s a myth that often leaves homeowners frustrated when they can’t achieve true comfort.

Common Causes of Poor Cooling

1. Poor Airflow to Rooms and Spaces

Restricted or dirty airflow is one of the biggest reasons your system struggles. Check for:

Dirty air filters
A dirty blower wheel (air handler)
A dirty cooling coil (often caused by pets, poor condensate drainage, or cooking residue being pulled into the system due to poor kitchen exhaust)
Bad ductwork design or leaks at joints and seams
Undersized return air grilles that cause high static pressure and lower airflow

2. Insulation and Ventilation Issues

Even a perfectly working HVAC system can’t keep up if your home isn’t sealed and ventilated properly. Problems include:

Insufficient attic or wall insulation
Poor attic ventilation (not enough intake or exhaust vents — or both)

3. Improperly Sized HVAC System

If your HVAC system wasn’t sized correctly for your home, it will never perform as expected. To know for sure, you’ll need a proper Manual J and Manual S calculation performed by a qualified professional.

What You Should Do

To get to the root of the problem:

Schedule a blower door test with an energy rater or HVAC company that offers this service.
Have a reputable HVAC company perform a thorough inspection.
Look for a performance-based contractor who specializes in HVAC load calculations — they’ll provide the most accurate answers and solutions.

Ready to Get the Most Out of Your HVAC System?

If your home won’t stay cool in the summer, don’t settle for excuses. The first step is an accurate HVAC load calculation to ensure your system is designed for comfort and efficiency.

At Rightway Performance Solutions, we specialize in helping homeowners get reliable, cost-effective solutions to their heating and cooling problems.