It's 7:00 AM on a freezing January morning in Palmdale. You look out the window and see a plume of white "smoke" rising from your outdoor heat pump. You rush to turn it off, convinced it's on fire.
Good news: It's probably not smoke. It's steam.
What is Defrost Mode?
When temperatures drop below freezing (which happens often in our high desert winters), ice can build up on the outdoor coils of your heat pump. If this ice gets too thick, the unit can't absorb heat from the air.
To fix this, the heat pump enters "Defrost Mode." It temporarily reverses itself, running in air conditioning mode to heat up the outdoor coils and melt the ice. The "smoke" you see is just the melting ice turning into steam in the cold morning air.
Signs It's Just Steam (Normal)
- It happens on very cold mornings.
- It lasts only 5-15 minutes.
- You might hear a "whoosh" sound. This is the reversing valve shifting pressure.
- The outdoor fan stops spinning. This helps the coil heat up faster.
Signs It's Actually Smoke (Call Us!)
- Smell of Burning. Steam has no smell. If it smells like burnt rubber or electrical wire, turn it off.
- Black or Dark Smoke. Steam is white. Dark smoke means something is burning.
- Lasts longer than 20 minutes. Defrost cycles are quick.
Still Worried?
If your unit is making loud noises or the ice never melts, you might have a bad sensor.
Check My Heat Pump