What is the reason for no cooling at idle but normal operation when driving?
2 Answers
Check if the air conditioning system is malfunctioning. Here is relevant information: 1. Reasons for air conditioning not cooling: Lack of refrigerant, car air conditioning needs to be refilled with refrigerant every 2~3 years. Refrigerant loss is usually due to leakage. If the car air conditioning does not cool, but starts cooling after refilling the refrigerant, consider whether there is a lack of refrigerant. Damage to the air conditioning flap, a relatively common issue is damage to the air conditioning flap motor. If there is a problem with the flap motor, it is relatively more troublesome. The flap motor is generally located in the middle of the dashboard, serving as the main switch for the air conditioning vents. Even if the air conditioning can cool, cold air can only come out through gaps, significantly affecting the cooling effect. 2. Hazards of running air conditioning at idle: When idling with the air conditioning on, instead of focusing on the economic cost caused by fuel consumption, more attention should be paid to the damage to the car and the increased later costs. When the engine runs at low speed and idle for a long time, the piston valves are more prone to carbon deposits. Excessive carbon deposits will directly affect fuel economy and also impact the performance and even the lifespan of the engine.
I've encountered this issue too—the AC doesn't cool at idle but works fine when driving. Most of the time, it's because the engine speed is too low at idle, and the AC compressor lacks sufficient power. The compressor is driven by the engine belt, so it spins slower at idle, reducing its ability to compress refrigerant. Another possibility is low refrigerant levels, where the system's low pressure at idle makes the issue more obvious. Clogged radiators or condensers with dust can also reduce cooling efficiency when parked due to lack of airflow. Over the years, I've found that cleaning the front grille and checking refrigerant levels can help temporarily. But for a real fix, it's best to visit a professional repair shop for a full system and wiring inspection—don't delay, or you'll suffer in summer heat.
