What are the reasons for no air coming out after running the car air conditioner for an hour?
4 Answers
The reasons for no air coming out after running the car air conditioner for an hour include poor heat dissipation of the air conditioner, slow rotation speed of the external fan or a dirty air conditioner; compressor damage; damage to the compressor's overheating protector; damage to the temperature sensor; and insufficient refrigerant, leading to poor cooling effect. Poor heat dissipation of the air conditioner: The main control switch may have poor contact, or the tightening screw between the motor and the fan blade of the blower may have loosened, causing the car heater blower to stop working. Use a multimeter to measure the contact resistance of the main control switch. If the resistance is too high or zero, it indicates a fault that should be repaired or replaced immediately. If the air conditioner blower stops working, it will cause subsequent heat dissipation issues, leading the air conditioning system to engage in high-pressure protection, which results in the protective shutdown of the air conditioning compressor. Severe internal wear of the compressor: This can prevent it from functioning normally. Since the compressor plays a crucial role in the air conditioning system—primarily compressing and delivering cold air—it operates in a high-speed rotation state for extended periods, which is one of the reasons it may fail to work properly. The compressor is mainly used to compress and deliver cold air. If there is a problem, check for any refrigerant leaks. Without cold air to compress or deliver, it naturally won't work.
I've seen this issue many times where the car's air conditioning stops blowing air after running for an hour. Nine times out of ten, it's because the fan motor's overheating protection has kicked in. When the fan runs continuously for an hour or so, especially on hot days with high load, the motor temperature rises and it automatically shuts off. It might start working again after cooling down, but this indicates the component is aging. It could also be a blown fuse—when the air conditioning circuit is under heavy load, the fuse may blow to protect the circuit. Additionally, the air conditioning system's electronic control module might be malfunctioning, especially in older cars where wiring connections are loose or corroded, causing signal interruptions and fan stoppage. Also, don’t forget to check the air conditioning filter; if it's dirty and blocks the air intake, the fan will struggle and may stop. In such cases, turn off the AC, take a break, open the windows for ventilation, and head to a repair shop as soon as possible to avoid bigger issues. Safety first—driving without AC in summer can lead to heatstroke and affect concentration.
My car had this issue before. During a countryside trip, the air conditioning suddenly stopped blowing air after running for an hour, making it unbearably hot. Through troubleshooting, I found out it was caused by a faulty blower motor resistor, where excessive current led to slow heat dissipation and triggered overheating protection. When driving normally, pay attention to sounds - if the fan noise becomes unusually loud or you smell burning, be alert. For inspection, you can first check the fuse box and use a wrench to tighten the fuses. If there are no warning lights on the dashboard, it's likely a minor issue. I recommend recording when and under what conditions the problem occurs, such as after prolonged sun exposure, to make repairs easier. In short, don't delay - AC failure isn't just uncomfortable but also a safety hazard. Address it promptly to ensure comfortable travels.
As a car enthusiast, I believe that when the AC stops blowing air, it's often due to the electrical system being overwhelmed. After running for about an hour, the blower motor may overheat, seize up, or slow down, requiring a cooldown to recover. Power management issues are also common, such as insufficient battery charge or an unstable alternator, causing the AC control system to lose power and shut off the fan. Additionally, if the evaporator freezes and blocks the vents, the airflow can drop to zero. For DIY troubleshooting, check for loose electrical connections and ensure the AC system's high and low-pressure lines are at normal levels. In daily use, avoid blasting cold air immediately after starting the car; gradually cooling down can extend the system's lifespan. The AC is a lifesaver in the car, and having it fail on a hot day is a real hassle. Sharing these tips in hopes that everyone pays more attention to these details.
