Why does the car still blow hot air when the AC is on?

[DelWeston]

Here are the reasons why the car still blows hot air when the AC is on: 1. Compressor overheating protection: Excessive load on the compressor causes its temperature to rise too high, triggering automatic protection. 2. Compressor overcurrent protection: Excessive load on the compressor or mechanical jamming causes the generator to suddenly deliver excessive current, resulting in compressor overcurrent protection. 3. Temperature sensor: Excessive air conditioning load or poor heat dissipation leads to excessively high condenser temperature. The signal from the temperature sensor will cause the air conditioning compressor to stop working. Car air conditioning refers to the air conditioning device installed in the vehicle, which can cool, heat, ventilate, and purify the air inside the cabin, providing a comfortable environment for passengers, reducing driver fatigue, and improving driving safety.

[VanDaniela]

As a seasoned driver, I've encountered the issue of hot air blowing from the AC several times. The most common cause is low refrigerant levels. If there's not enough refrigerant, the compressor can keep running but it won't help—the air will still be hot. Another issue is when the temperature control knob gets stuck. Even if you turn it to the blue cooling zone, the internal linkage might be rusted and stuck, still directing air through the heater core. It's also quite common for the blend door actuator to fail. If this part stops working, the heater core will keep mixing in warm air. And if the compressor doesn't start, it's useless—check if the AC pressure switch is broken. Last time my car was blowing hot air, I found out it was due to poor contact in the AC panel buttons—the cooling mode wasn't properly engaged. If you face this problem in summer, don't tough it out. Get it checked immediately, otherwise the car interior turns into a sauna, which not only risks heatstroke but also makes you drowsy and prone to accidents.

[DiVivian]

Last time my car's AC was blowing hot air, I thought I'd check it myself first. First, I checked if the temperature setting was correct, making sure I didn't accidentally turn it to the red high-temperature zone. Then, I tried pressing the AC button to see if the indicator light came on—sometimes the button fails and the light doesn't turn on. Next, I popped the hood to listen for any noise from the compressor; if there's no sound, it might be a broken clutch or a blown fuse. I also checked the AC lines for frost or oil stains—if present, it means there's a refrigerant leak. Finally, I inspected the coolant level to ensure it wasn't too low for proper circulation and heating. My advice is not to disassemble things randomly; just take it to a shop for a professional pressure test. If it's low on refrigerant, a top-up will do, and replacing parts usually costs just a few hundred bucks—still better than driving in a sauna on a hot day.

[StBriella]

It's really annoying when the air conditioner still blows hot air. I've encountered several reasons for this. The most frustrating one is when the temperature control knob is broken. Even when turned to the lowest setting, the AC insists on blowing hot air. Another issue is when the automatic AC malfunctions due to incorrect data from the outdoor temperature sensor, causing the system to mistakenly blow hot air. My best friend's car had a problem where the small radiator was leaking, allowing engine heat to seep into the AC ducts. There's also a less common reason: if you've recently had your windshield replaced, the repair shop might not have properly installed the temperature sensor wiring. It's advisable to always turn off the AC button before shutting down the system, then let the fan run for a few minutes to remove moisture, which helps prevent mold in the ducts. If you frequently take short trips, it's best to drive on the highway once a month to let the compressor run longer, protecting the refrigerant and the piping system.