A heat pump usually won’t cool on very hot days because airflow is restricted, refrigerant is low, or the outdoor coil can’t shed heat fast enough. The most common real-world cause is a dirty filter or clogged outdoor unit that starves the system of airflow. In extreme heat, even a healthy heat pump can reach its limits and run continuously while holding only a small temperature drop indoors. Thermostat settings, an iced coil, or a failing outdoor fan can also block cooling. Our licensed technicians see these patterns across the Upland area every summer and can separate normal capacity limits from repair-worthy faults.
Try these quick checks before calling:
- Set the thermostat to Cool and Auto, not On.
- Replace a dirty filter and open closed supply vents.
- Rinse debris from the outdoor coil and clear 2–3 feet around it.
- Look for ice on lines or the coil and let it thaw before restarting. If basic checks don’t help, power the system off to prevent compressor damage and schedule a professional diagnosis.
Updated: 2026-03-31
Need help in Upland, IN? Call (765) 613-0053 or book online. "Craig and Alexander did a bang up job installing my new heat pump." — Bill M.