Why Is My Air Conditioner Blowing Cold Air or Making Strange Noises in Winter?
All reverse cycle ducted, split system, and room air conditioning systems are affected by the outdoor temperature — the colder it is outside, the harder it is to generate warm air inside. When temperatures drop, most systems will form ice or frost on the outdoor unit. To deal with this, they automatically enter a defrost cycle. This is completely normal and includes the following:
Air Conditioner Outdoor Unit Icing Up
What to Expect During Defrost
- Steam or Smoke Appearance: As the system melts ice, it creates steam — sometimes mistaken for smoke. You may also notice large amounts of water around the outdoor unit. This is normal.
- Loud Noises: You may hear a loud whooshing sound or other noises such as buzzing, cracking, or gas flowing through the system. These sounds are also normal, especially for inverter systems as the compressor speeds up or slows down.
- Outdoor Fan May Stop: Some systems stop the fan motor during defrost while the compressor continues to run. This behaviour is expected.
- Cold Drafts Indoors: During defrost, the indoor unit may blow a brief cold draft through the outlets.
- Split and Room Systems: You may also hear cracking or gas ‘whooshing’ noises from the indoor unit. This is typical operation.
Air Conditioner Outdoor Unit Condensating
Important Notes
- Leave the System Running: Let the defrost cycle complete fully. If the unit is switched off mid-cycle, it may remain stuck in defrost mode after being turned back on.
- Defrost Duration: The process should last no longer than 5 minutes. If it runs longer, a service call may be required.
- Don’t Hose Down the Unit: Never spray or pour water on an iced-up outdoor unit — this can damage electrical components.
If you’re still unsure or think something isn’t right, a technician can inspect the unit on-site.