Why Is My Heat Pump Not Cooling on Hot Days?

A heat pump not cooling on hot days usually means there’s a problem with refrigerant charge, airflow, controls, or the reversing valve. The most common cause we see is low refrigerant from a leak, which prevents heat from being absorbed and moved outside.

Other frequent culprits include a clogged filter or dirty indoor/outdoor coil restricting airflow, a thermostat or control issue keeping the system from switching modes, a stuck reversing valve leaving the unit in heat, or a compressor/contactor fault that stops proper operation. A technician will verify airflow, measure the refrigerant charge, check for leaks, inspect electrical connections, and confirm thermostat and control operation per our standard checklist. We handle these exact issues across the Danville area and also offer flat-rate pricing with 24/7 emergency service.

Try these quick checks before you call:

• Replace or clean the air filter if it’s dirty.
• Confirm the thermostat is set to Cool and a lower temperature than the room.
• Clear leaves or debris from around the outdoor unit so air can move freely.

If cooling doesn’t return after these checks, turn the system off and schedule a professional diagnosis to prevent further damage.

Updated: 2026-04-01

Need help in Danville, IL? Call 217-247-4108 or book online.