What are the reasons for the air conditioner not blowing hot air?

[LuciaLynn]

The reasons for the air conditioner not blowing hot air are: 1. The heater core has malfunctioned; 2. The water valve of the heater core has malfunctioned. The car air conditioner heating system utilizes the engine's heat. The functions of the air conditioner are: 1. To adjust and control the temperature, humidity, air cleanliness, and air flow inside the compartment to an optimal state; 2. To provide a comfortable riding environment for passengers and reduce travel fatigue; 3. To create good working conditions for the driver and ensure driving safety. Precautions when using the air conditioner include: 1. Choose an appropriate air conditioner temperature; 2. Do not immediately activate the internal circulation when entering the car in summer; 3. Do not leave the air conditioner on for extended periods; 4. Do not arbitrarily adjust the direction of the air vents; 5. Use the air conditioner in a fully enclosed state; 6. Avoid resting or sleeping for long periods in a stationary car with the air conditioner running.

[LaCharles]

I'm annoyed that my car's AC isn't blowing hot air when I drive. Common causes include insufficient coolant, which means there's not enough liquid circulating to generate heat; a clogged heater core with accumulated dust and debris in the pipes; or a faulty temperature controller or blend door actuator, preventing the system from switching to heat mode. Additionally, a dirty cabin air filter can block airflow, or the temperature setting might be incorrect (set to cooling). If the engine hasn't warmed up yet, it won't produce hot air either. You can first check the coolant reservoir level and top it up if low, and verify the mode settings. Driving in winter without heat is dangerous—don't delay, get it checked at a repair shop. Regular maintenance, like replacing filters, also helps.

[AbelRose]

Based on my experience in car repairs, the lack of hot air from the AC is often caused by a clogged heater core, insufficient coolant due to leaks, or a stuck blend door actuator failing to switch modes. Faulty sensors in the control system can also cause errors, such as a malfunctioning thermostat failing to detect temperature. Additionally, dirty filters can block hot air output, and abnormal fan speeds can affect airflow. The simplest check is to inspect the coolant level and color, replacing it if it's too old. Long-term neglect of these issues may lead to a high risk of engine overheating, so regular maintenance and early intervention are recommended.

[DeJohnny]

Having driven for decades, I've encountered the issue of no hot air from the AC multiple times. The most common cause is low coolant level, followed by a clogged heater core. It could also be due to the air door stuck in the cold position or control system failures like switch damage. The solution is to first top up the coolant and set the temperature to hot air mode. If that doesn't work, further investigation is needed. Avoid driving with the AC on cold for extended periods as it can cause significant system damage. Regularly monitor the coolant temperature gauge to prevent potential issues.