Autumn is around the corner, and the chill forces many to switch their home split systems to heating mode. But what should you do if you pressed the right button on the remote, yet the air conditioner shows no signs of life, the louvers won't open, or the system blows cold air at you? A familiar situation, isn't it?

✅ Answer
The most common "breakdown" is actually a system startup delay (compressor protection) and a pre-heating mode. When switching to "Heat" (often a sun icon), the air conditioner intentionally keeps the indoor fan off for 5 to 15 minutes. It needs time to warm up the heat exchanger so it doesn't blow freezing outside air at you. You just need to wait!

Main Reasons for Lack of Heat

If more than 15 minutes have passed and there's still no heat in the room, check the following factors:

Potential issues and limitations:
  • Too cold outside: Most standard (non-inverter) air conditioners can only heat when outside temperatures are down to 23°F (-5°C). If it's colder, the oil in the system thickens, and the compressor physically cannot start. Check your manual—not everyone understands what type of AC they have or how it operates.
  • Incorrect remote settings: Ensure that the "HEAT" mode (Sun icon) is selected, and the temperature is set noticeably higher than the current room temperature (e.g., set it to 82°F-86°F / 28°C-30°C to test). However, if your issue is related to the first point, do not do this.
  • Freon shortage: If the refrigerant pressure has dropped due to a micro-leak, the split system loses efficiency and can neither cool nor heat the air. A refill is required. This is an important point for those ready to throw their AC away immediately.
ℹ️ Note: If the split system runs on heat for a long time, the outdoor unit may become covered in frost or ice. The automation will periodically stop pumping heat into the apartment to activate a defrost cycle (a drop icon, "Defrost", or "Pre-Def" will light up). Do not unplug the appliance during this time; let it defrost!

Quick Diagnostic Table

Below is a basic table to help you determine the next steps:

Symptom Possible Cause Solution
Heating turned on, blows cold for 5-10 mins Heat exchanger is warming up Do not press anything, wait 15 minutes
Defrost / Pre-Def light is blinking Automatic defrost cycle triggered Leave the AC on, wait
Indoor unit does not respond to remote at all Dead batteries or frozen control board Replace batteries, flip the circuit breaker off for 2 minutes

Automating the Climate in Your Room or Home

To avoid freezing while waiting for the system to heat up the room (since it isn't instant), using automation is highly convenient. You can set the device to start exactly an hour before you return home. We covered this in detail in our step-by-step guide: how to set the timer on a Centek split system and other popular brands.

❓ Can I turn on the AC in winter during severe frost?
It depends on your AC type. Premium inverter models (and heat pumps) can run stably at temperatures down to 5°F (-15°C) or even -13°F (-25°C). Standard on/off systems are strictly limited to 23°F (-5°C). Always check your model's technical manual before turning it on—we emphasize this once again. Such equipment is not cheap.