Why does the air conditioner suddenly stop blowing hot air?

[LeMia]

If the air conditioner suddenly stops blowing hot air, it may be caused by the outdoor unit shutting down completely. The main reasons are as follows: 1. The indoor unit control board stops working after a few minutes, which is caused by the outdoor unit's power supply. This may be due to the outdoor unit's operating current being too high, causing the indoor unit board relay to be unable to handle the maximum current value. 2. The outdoor unit compressor overheats and triggers protection. Poor heat dissipation of the outdoor unit or excessive aging of the compressor can cause the compressor temperature protection switch to shut down. The most common solution to this problem is to clean the outdoor unit condenser or check the outdoor fan speed. 3. The four-way valve coil loses power. If the air conditioner still heats, it indicates that the four-way valve is damaged.

[LaJoy]

I recently encountered the issue of the AC not blowing hot air, mainly due to low coolant levels or a leakage problem, since the car heater relies on engine heat transfer. Another possible cause is a faulty thermostat that can't activate the heating mode, or a stuck blend door that won't open. If this happens while driving in winter, the car interior can feel extremely cold, affecting comfort, and may also cause window fogging, impairing visibility. So, I recommend promptly checking the coolant reservoir under the hood for any discoloration or reduction. It's best not to tamper with the electrical circuits yourself to avoid damaging more components—just take it to a professional shop for inspection and timely resolution to prevent driving hazards.

[Jameson]

My experience is that when the AC isn't blowing hot air, first check the cooling system and damper components. Common issues include insufficient coolant leading to failed heat transfer or blown fuses preventing the blower from operating. In such cases, I'd turn on the interior fan to test airflow - sometimes manually adjusting the temperature control knob can provide a temporary fix. But be careful not to overlook clogged filters, as dirt buildup reduces airflow and increases energy consumption. DIY repairs can save money, but when it comes to electronic control components, it's better to have a professional technician diagnose with proper tools. Otherwise, minor issues might escalate into complex problems. Remember, safety always comes first - it makes repairs more reassuring.

[OAlyssa]

I think it's very dangerous when the air conditioning suddenly stops blowing hot air, especially in cold weather, as it can cause frostbite or blurred vision leading to accidents. The reasons are usually a leaking or cracked heater core preventing heat circulation, or a cooling system malfunction, possibly due to a faulty temperature control sensor. I would immediately pull over to the roadside, turn on the ventilation mode to circulate air, and contact rescue services without delay to avoid greater losses. Timely inspection can prevent long-term damage, making driving safer and reducing unnecessary repair costs.