Why does the car emit a burning smell when the air conditioning is on?

[WillowFitz]

The reasons for a burning smell when the car's air conditioning is on are as follows: Mold has formed on the surface of the heat exchanger fins. Below is relevant information about the car's air conditioning system: 1. Compressor: Driven by the engine, it continuously draws in the low-temperature, low-pressure refrigerant vapor generated by heat absorption and vaporization in the evaporator, compresses it to form high-temperature, high-pressure refrigerant vapor, and discharges it to the condenser, creating high-pressure conditions for the refrigerant to continuously condense and release heat in the condenser. At the same time, it overcomes the circulation resistance of the refrigerant in the refrigeration circuit. 2. Condenser: It releases the heat contained in the high-temperature, high-pressure refrigerant vapor discharged by the compressor to the outside air flowing through the condenser and condenses the refrigerant vapor into refrigerant liquid with a certain temperature. Most condensers are located in front of the radiator at the front of the car and are cooled by the cooling fan and the incoming airflow generated by the car's movement.

[SpencerRose]

Last time I drove my car, there was a burning smell from the AC, which was really scary. The mechanic explained that it might be due to the electromagnetic clutch of the AC compressor burning out, caused by long-term overload operation leading to high temperatures melting the parts and producing the odor. Aging wires short-circuiting is another reason, especially in older vehicles with outdated electrical systems, which can easily cause a fire. A clogged AC filter with accumulated dust or foreign objects burning inside could also be the culprit. I suggest immediately turning off the AC system, finding a safe place to park, opening the hood to check for any signs of smoke, and avoiding DIY repairs on the electrical system due to the high risks. It's best to call a professional technician to inspect and replace any faulty parts to prevent more serious malfunctions. Don't forget to regularly replace the filter and clean the ducts to maintain safety, as this smell is hazardous and can affect respiratory health.

[McJuniper]

I've been into cars for many years and encountered similar situations several times. When the air conditioner emits a burnt smell, common factors include the fan belt slipping and overheating, causing friction and igniting the smell, or the compressor relay burning out or wiring harness aging and leaking electricity, generating heat. If leaves or accumulated dust enter the air conditioning system, they can also burn under high temperatures. When working on it yourself, avoid touching the electrical parts to prevent electric shock. First, check the belt tension for cracks or smoke. Promptly visit a repair shop to clean the evaporator and replace fuses. During routine maintenance, pay attention to cleaning the air intake and regularly replacing the filter to effectively avoid these issues. Don’t overlook electrical problems—fix them early to ensure a safe and worry-free drive.

[VonEsther]

With decades of driving experience, I've seen it all. A burning smell when turning on the AC usually indicates electrical faults like a burnt-out compressor or short circuits causing minor fires. When you notice a pungent odor, immediately turn off the AC and shut down the engine to inspect under the hood. If inexperienced, avoid tampering to prevent accidents. Visit a trusted auto repair shop for a thorough inspection to prevent roadside emergencies.