How to Determine the Condition of a Car Compressor?
2 Answers
Here are the relevant methods for determining the condition of a car compressor: 1. Checking the compressor's sealing: Since refrigerant has strong permeability, the sealing condition of the compressor significantly affects the air conditioning system. The method to check the compressor's sealing is: Use a manifold gauge to test, connecting the high and low-pressure hoses of the manifold gauge to the compressor's high and low-pressure service valves respectively. Start the engine and let it run at idle speed with 2000r/min. When the compressor is working normally, you can hear the metal sound of the piston movement inside the compressor. The normal working low-pressure reading should be 0.15~0.20MPa, and the high-pressure reading should be 1.42~1.47MPa. 2. Measuring the resistance value of the compressor's electromagnetic clutch: First, remove the electromagnetic clutch coil from the compressor, then use a multimeter to measure its resistance. Since the standard resistance of the electromagnetic clutch coil is (3.7±0.2)Ω, use the ohmmeter function of the multimeter to avoid measurement errors. If the multimeter's pointer does not move during measurement, it indicates that the electromagnetic clutch coil is open. If the measured value is less than 3.5Ω, it indicates a short circuit or open circuit in the coil, or the electromagnetic coil should be replaced. 3. Checking the compressor's operating condition: Check if the drive belt is broken or loose. If the drive belt is too loose, it will slip, accelerate wear, and fail to transmit power. Check for any noise inside the compressor and if the compressor clutch is slipping.
After driving for so many years, I can recognize the sound of a broken compressor with my eyes closed. Start the car and turn on the AC—if there's a clanging metal sound under the hood, the compressor is most likely done for. Set the dashboard temperature to the coldest and the fan to max, wait five minutes, then feel the AC pipes: if the low-pressure pipe is warm instead of icy, or if there's no noticeable temperature difference between the two pipes, the compressor isn’t doing its job. Nowadays, cars have pressure gauge ports—hook one up, and if the high and low-pressure readings are off, the compressor is definitely to blame. Once, my neighbor’s car had a compressor that sounded like a tractor when running. We took it apart and found all the bearings inside shattered.
