Owners of heat pump mini-splits are often surprised when the indoor unit stops blowing warm air on a cold morning while the outdoor unit hisses or releases steam. In most cases this is a normal defrost cycle.
What Defrost Looks Like
- The indoor fan slows or stops for several minutes.
- The outdoor unit may make a whooshing sound or release a cloud of vapor.
- Heating resumes on its own afterward.
When to Be Concerned
- The outdoor unit stays encased in thick ice and never clears.
- Defrost cycles happen constantly, and the room never warms.
- The indoor unit shows an error code or flashing lights.
Owner-Level Checks
Keep snow and debris clear of the outdoor unit and make sure meltwater can drain away from it. Do not chip ice off the coil or pour hot water on it, and never open the outdoor unit’s panels; they contain high voltage and refrigerant components.
If defrost does not clear the ice, a sensor, fan, control or refrigerant problem may be involved. Book a mini-split repair visit.