Why Is My Ductless Heat Pump Indoor Unit Freezing Up?
Published: July 21, 2026 — BC Wide Home Services Ltd, doing business as BC Wide Heating & Air Conditioning — Greater Vancouver, BC
Common Causes of Indoor Coil Freezing
A dirty air filter is the most common cause — restricted airflow causes the coil temperature to drop below freezing. Low refrigerant charge also causes freezing. A blower fan not running at full speed due to a faulty motor or capacitor. Running the fan on low speed in high humidity conditions. A restricted condensate drain causing water to sit on the coil and freeze.
What to Do If You See Ice
Turn off the system immediately and switch to fan-only mode to help thaw the coil. Do not run the system in cooling mode with a frozen coil — this can damage the compressor. Check and clean the air filter. Allow the coil to thaw completely (2-4 hours) before restarting. If the problem recurs, call for professional service.
Prevention Tips
Clean the air filter monthly during heavy cooling season. Use AUTO fan speed (not low) — the slower the fan, the colder the coil gets. Ensure nothing is blocking the indoor air intake or outlet. Schedule annual professional maintenance including refrigerant charge check and coil cleaning.