What Causes the Passat's Air Conditioning to Not Cool at Idle?
2 Answers
Passat's air conditioning not cooling at idle can be attributed to the following specific reasons: Damaged Expansion Valve: A damaged expansion valve prevents the formation of high pressure in the system before the valve, resulting in the high-pressure refrigerant failing to reach 150Kpa. This causes the evaporator after the expansion valve to not cool down, leading to ineffective air conditioning. Internal Wear of the Air Conditioning Compressor: This causes the pressure between the air conditioning compressor and the expansion valve to not reach 150Kpa to 200Kpa, preventing the refrigerant in the system from circulating normally and resulting in ineffective air conditioning. Refrigerant Leakage: Insufficient refrigerant in the air conditioning system reduces the amount of refrigerant sprayed into the evaporator from the expansion valve. Consequently, when the refrigerant evaporates in the evaporator, the amount of heat absorbed decreases, leading to a reduction in cooling capacity.
My Passat also experienced the issue of insufficient cooling from the AC at idle. This is usually because the engine speed is low at idle, and the AC compressor may not operate at full capacity. First, insufficient refrigerant is a common cause. If there's a leak, the system's cooling efficiency drops significantly, requiring timely refilling and repair. Second, faults in the compressor itself, such as piston wear or clutch failure, are more likely to manifest at idle. It's also important to check if the fan is working properly. If the condenser fan fails, heat can't dissipate, and the AC won't cool effectively. Additionally, electrical issues like relay failure or sensor damage can interrupt the cooling cycle. It's recommended to visit a professional workshop for a pressure test on the refrigerant and compressor. Avoid DIY repairs to prevent exacerbating the problem, as safety comes first, especially when parked, as it affects driving visibility.
