A heat pump may stop cooling on hot days due to low refrigerant, blocked airflow, or failed electrical parts. The most common issues are a dirty filter or coil that chokes airflow and a refrigerant charge that has fallen out of spec. Other causes include a stuck defrost control, tripped breakers, or a weak run capacitor that keeps the compressor from starting. During heat waves, our technicians often find undercharged systems or weak capacitors in homes around Maryville.
Try these quick checks before a service call:
- Set the thermostat to Cool and Fan on Auto, not On.
- Replace the air filter and clear vegetation/debris around the outdoor unit.
- Check breakers; if the outdoor unit is silent, the capacitor may be bad.
- Look for ice on refrigerant lines; if present, shut the system off to thaw.
If basic checks don’t help, turn the system off to prevent damage and schedule a professional diagnostic.
Updated: 2026-04-01
Need help in Maryville, TN? Call 865-658-8450 or book online. "Our heat pump/AC problem was scheduled and handled promptly. Our tech, Logan, was polite, professional and we could not ask for a better experience." — Michael W.