How to Determine if a Compressor is Good or Bad?
2 Answers
Methods to determine if a compressor is good or bad are: 1. Use a multimeter to measure its resistance. If the sum of the resistance between SC and RC equals the resistance between RS, the compressor is normal. If the resistance deviates significantly or there is no resistance between the three, the compressor is damaged; 2. Use a multimeter to check the power supply. If it shows power is being supplied but the compressor does not start, you can replace the starting capacitor. If the compressor still does not start after replacing the capacitor, the compressor is damaged. The working principle of a compressor is: it draws refrigerant from the low-pressure area, compresses it, and sends it to the high-pressure area for cooling and condensation. The heat is dissipated into the air through the radiator, and the refrigerant changes from a gaseous state to a liquid state, increasing the pressure.
With years of experience in car repair, I have practical methods to judge the condition of a compressor. Start the engine, turn the AC to maximum, and listen closely to the compressor sound in the engine bay: a normal operation produces a slight hum, while abnormal sounds include rattling or metal grinding. Touch the compressor housing or pipes to feel the temperature—overheating indicates internal issues. Use a pressure gauge to check high and low pressure readings; normal low pressure is around 30 psi, and high pressure is about 150-200 psi. Look for oil leaks, as oil stains may indicate a faulty seal. If the clutch engages poorly, it’s often due to a blown fuse or aging wiring. Regular maintenance can extend the compressor’s lifespan. If anything seems off, get it repaired promptly to avoid cooling failure, which affects driving safety. This method is highly practical—when car owners report poor cooling, I often follow these steps to diagnose the issue.
