Why is My Heat Pump Iced Up?

Ice on Your Outdoor Unit: Normal or Big Problem?

In Tehachapi, it's common to wake up in January and see your heat pump (the outdoor unit) covered in a light layer of frost. This is normal. But if your unit looks like an igloo, encased in thick ice, you have a problem.

How Heat Pumps Work in Winter

Heat pumps don't generate heat; they move it. Even in 30°F air, there is heat energy. The heat pump extracts this heat and pumps it indoors. As a byproduct, the outdoor coil gets very cold—colder than the outside air. Condensation forms on the coil and freezes.

The Defrost Cycle

Modern heat pumps have a "Defrost Mode." Every 30-90 minutes, the unit will:

1. Switch into cooling mode temporarily (to heat up the outdoor coil).
2. Turn off the outdoor fan (you might see steam rising).
3. Turn on backup electric heat strips (so you don't feel cold air inside).
4. Melt the ice on the outdoor coil.

When to Call a Pro

If the ice never melts, or if it builds up so thick that it's crushing the fins, your defrost board or sensors might be broken. Other causes include:

• Low Refrigerant: Verify this with a tehc.
• Snow Burial: As mentioned in our safety guide, deep snow can block airflow, preventing the unit from defrosting properly.
• Bad Fan Motor: If the fan doesn't run, the unit can't pull air across the coil.

The "Dual Fuel" Solution for Tehachapi

Standard heat pumps lose efficiency rapidly when temperatures drop below 30°F. For Tehachapi homes, we often recommend a Dual Fuel system: a heat pump for mild days (35°F-55°F) and a propane furnace for the freezing nights.

This setup gives you the cheapest electric heating during the day and the powerful warmth of gas when you need it most.