Why is there no hot air when the air conditioner is turned on?

[Angelina]

There are several situations when the air conditioner does not produce hot air: 1. The heating function of the air conditioner takes about 5-10 minutes longer than cooling to start blowing air because the preheating time has not yet been reached. 2. The four-way valve is not open, or the four-way valve itself is stuck, or the electronic control does not output voltage to the four-way valve. 3. There may be a lack of refrigerant, as heating requires slightly more refrigerant than cooling. 4. The indoor pipe temperature sensor may be damaged. After starting operation, the compressor and fan motor of the outdoor unit need to run for a while before the indoor unit's fan motor begins to blow air. This is to ensure that no cold air is blown out from the indoor unit, making people feel uncomfortable, which is the so-called "anti-cold air" function.