Why Is My Heat Pump Not Cooling on Hot Days?

A heat pump that won’t cool on hot days usually has restricted airflow, a refrigerant issue, or a control problem. Most often, a clogged filter or a blocked outdoor coil causes the system to overheat and lose capacity. Thermostat mis-settings, a sticking reversing valve (the part that switches between heat and cool), or low refrigerant can also limit cooling. On 95°F afternoons, a slightly undercharged system may cool early but fall behind by mid-day. Our technicians see these patterns throughout Birmingham’s humid summers and can diagnose them quickly. For urgent breakdowns, Wilbur’s offers 24/7 heat pump repair.

Try these quick checks before you call:

• Replace or clean the air filter and open all supply vents.
• Gently rinse debris off the outdoor coil with power off.
• Confirm thermostat is on Cool, Auto fan, and set 3–5°F lower than room temp.
• If you see ice on lines or hear short cycling, shut the system off and call. A spring and fall tune-up, with a clean filter between visits, helps avoid most hot-day cooling failures.

Updated: 2026-04-06

Need help in Indian Springs Village, AL? Call (205) 675-0280 or book online. “I actually was able to get same day repair service to fix my heat pump… I’m sitting in a cool house now thanks to Wilbur’s!” — Kurt G.