What are the symptoms of a faulty electromagnetic valve in a car's air conditioning compressor?

[JulietteMarie]

When the electromagnetic valve of a car's air conditioning compressor fails, the following symptoms may occur: 1. Engine speed: When the AIC switch is turned on, observe whether the engine speed increases (you can check the tachometer in the cabin). If the engine speed increases when the air conditioning is turned on, it indicates that the compressor control circuit is functioning properly. If the engine speed does not increase, it suggests damage to the compressor control circuit or a faulty electromagnetic clutch in the compressor. 2. Compressor clutch engagement: Another scenario is when the engine speed increases and the compressor clutch engages, but the air conditioning compressor seizes and becomes inoperable. If the compressor fails, it could be due to refrigerant contamination with water or a damaged oil seal, allowing non-compressible liquid to enter the compressor and damage the piston. However, this situation is uncommon, and most compressor failures are primarily caused by issues with the electromagnetic clutch.