How to Check the Condition of a Compressor?
3 Answers
Compressor's resistance between RS equals the sum of SC and RC resistances, which can be used to determine its condition. Below are extended details: 1. To assess the compressor's condition, first identify its three terminals: S, R, and C. S is the start winding, R is the run winding, and C is the common terminal. 2. Then, use a multimeter to measure the resistances. The sum of SC and RC resistances should equal the RS resistance under normal conditions. 3. If the resistances deviate significantly or show no reading between any two terminals, the compressor is damaged. 4. Even if the multimeter readings appear normal, internal short circuits may not be detected. A simple method is to check for power using the multimeter. If power is present but the compressor doesn't start, replace the start capacitor.
To check if the compressor is working properly, I usually start with the simplest method. First, start the car engine and turn the air conditioning to the coldest setting. Then, stand by the car and listen to the sound when the compressor starts up. A normal compressor will produce a slight humming sound. If you hear a clicking noise or a harsh screeching sound, there’s likely a problem. Next, open the engine hood and inspect the compressor’s belt: shake it by hand to see if it’s loose, and if there are cracks on the surface, replace it immediately. Otherwise, excessive wear can affect performance. Then, use a thermometer or an infrared gun to measure the temperature of the air vents—it should be around 6 to 10 degrees Celsius for optimal performance. If it’s too hot, it’s a red flag, possibly indicating the compressor clutch isn’t engaging or the system is clogged. During regular maintenance, also check for oil stains or refrigerant leaks around the compressor, as this can help avoid major repairs. If you’re unsure, take the car to a professional shop to test the high and low pressures—it’s more accurate. Remember, don’t skimp on this small expense, as driving with a broken AC is really uncomfortable.
When encountering abnormal compressor issues, I first observe daily driving scenarios. If the air conditioning doesn't blow cold air or takes too long to cool while driving, the compressor might be faulty. Simultaneously, pay attention to engine compartment sound changes - a properly working compressor usually produces a steady humming noise, while clicking or rattling sounds serve as warnings. I often pop the hood after parking to inspect the compressor belt condition: looseness or wear requires adjustment. Temperature testing is simplest - use a small thermometer at the air vents, with higher readings indicating cooling failure. Regular refrigerant top-ups can prevent issues, though most compressor failures involve clutch malfunctions or internal wear, making professional shop testing more efficient for actual problems.
