Fault Analysis Method of Air Conditioning and Refrigeration System

Take a Look: After Watching the Air Conditioner Run

Look at the refrigerant flow in the glass observation window, and the uniform and transparent liquid is normal.

Looking at the frosting of the low-voltage circuit, the surface frosting is normal.

Look at the leakage at each joint of the refrigeration system, and it is normal to be dry without oil stains.

Look at the working condition of the magnetic coil of the compressor, it is normal if the compressor can be turned on after being sucked in and there is no abnormal noise. Look at the water dripping condition of the evaporator. Generally, the air conditioner runs for about 8 minutes, and it is normal that the water drips out from the water receiving plate of the evaporator.

Check to see if the condenser electronic fan is operating normally.

Second listening: After listening to the air conditioner running

There is no noise or impact sound when the compressor is running, but it is abnormal.

Listen to the evaporator blower, condenser electronic fan, motor, etc. for noise, and it is abnormal.

Three touches: After the air conditioner is running

Touch the high and low pressure pipelines of the refrigeration system. It is normal for the high pressure pipeline to be hot and the low pressure pipeline to be cold.

The condenser heat is normal, and there is a temperature difference from the bottom to the top of the condenser, it is normal that the drying filter is warm, and there is no obvious temperature difference between the inlet and the outlet, it is normal.

There should be a significant temperature difference before and after the expansion valve, which is normal.

It is normal for the wind blowing from the air outlet in the car to feel cold.

Four tests: After the air conditioner is running

1. Detect leaks with leak detectors

Use a leak detector to check for leaks at all joints throughout the system.

2. Check with a multimeter

Use a multimeter to check the air conditioning circuit to determine whether there is a short circuit or open circuit fault in the air conditioning system circuit.

3. Check with a thermometer

A thermometer can be used to determine the failure of the condenser, evaporator, and accumulator.

When the evaporator is working normally, the lower the surface temperature of the evaporator without frost, the better. When the condenser is working normally, the temperature of the inlet pipe of the condenser is 70℃ and the temperature of the outlet pipe is about 50℃. When the accumulator is working normally, The temperature of the accumulator should be about 50℃. If the temperature of the liquid accumulator is inconsistent, it means that the accumulator is blocked.

4. Check with a pressure gauge

Connect the high and low pressure gauges of the manifold pressure gauge to the maintenance valves of the exhaust and suction ports of the compressor respectively. When the air temperature is 30°C~50°C and the engine speed is 2000r/min, check that the fan speed is adjusted to high-grade, and the temperature is adjusted to the coldest gear. The normal conditions are:

The pressure at the high pressure side should be 1.421~1.470MPa, and the pressure at the low pressure side should be 0.147~0.196MPa, otherwise it means that the air conditioning and refrigeration system is faulty.