How to Identify Whether a Car Air Conditioning Compressor is Good or Bad?
2 Answers
Here are the methods to identify whether a car air conditioning compressor is good or bad: 1. Check the sealing of the compressor: Use a manifold pressure gauge to test. Connect the high and low-pressure hoses of the manifold pressure gauge to the high and low-pressure service valves of the compressor, respectively. Start the engine and let it run at idle speed with a rotation of 2000r/min. 2. Measure 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 needle 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 that the coil is short-circuited, open, or the electromagnetic coil should be replaced. 3. Check the operating state of the compressor: Whether the drive belt is broken or loose—if the drive belt is too loose, it will slip, accelerate wear, and fail to transmit power; whether there is noise inside the compressor; whether the compressor clutch is slipping.
After driving for so many years, I've summarized a few tips to identify whether the air conditioning compressor is working properly. After starting the car and turning on the AC switch, listen carefully for a clicking sound from the engine compartment—that's the sound of the compressor clutch engaging. Then, feel the temperature of the air vents; if the air isn't cool or doesn't get cold within five minutes, there's likely an issue. Also, pay attention to the sound of the compressor running—normally, it should be a steady hum. If you hear strange noises like screeching or clunking, it's a warning sign. Last time, my car's belt was loose, which also affected cooling, so remember to check the belt's tension and for any cracks. For older cars, pay special attention to oil stains on the AC pipes—that's a sign of refrigerant leakage. If you're really unsure, take it to a repair shop to test the high and low pressures; the mechanic can tell right away with a pressure gauge.
