How to Identify Whether a Car Air Conditioning Compressor is Good or Bad?

[VanCharlie]

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.

[VonVivienne]

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.

[DiJoy]

I enjoy tinkering with my car, and there are three simple steps to check the compressor's condition. First, inspect the belt: pop the hood and check the compressor belt—if it's loose or cracked, it needs replacing. Next, test the clutch: start the engine and turn on the AC, then observe if the compressor pulley engages and spins. If it doesn’t move, check the fuses and wiring; if it spins weakly with unusual noises, the compressor needs replacement. Finally, feel the lines: after running the AC for ten minutes, the silver low-pressure line should feel icy cold, while the black high-pressure line should be hot—this is normal. A small temperature difference indicates poor compressor performance. Last time, I noticed frost on the low-pressure line, which meant low refrigerant levels were affecting the compressor.

[FinleyLee]

The most obvious sign of air conditioning compressor failure is loss of cooling. When you press the AC button, hot or slightly cool air blows from the vents, and it still doesn't get cold after twenty minutes. Also pay attention to abnormal noises, such as metal grinding sounds or sudden clicking noises. Once, my friend was driving when the compressor suddenly made tractor-like noises - turned out the piston had seized. Don't ignore small symptoms; leaving a broken compressor unrepaired can lead to the entire AC system being scrapped. Replacing a whole new system could cost as much as half a year's fuel expenses.