Look: after the air conditioner is running

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

Look at the frosting condition of the low-voltage circuit. The frosting on the surface is normal.

Check the leakage at each joint of the refrigeration system. It is normal if it is dry and free of oil stains.

Check the working condition of the magnetic coil of the compressor. It is normal to see the water flowing from the evaporator if the compressor can rotate after being sucked in and there is no abnormal noise. Generally, the water flowing from the water tray of the evaporator is normal when the air conditioner runs for about 8 minutes.

Check whether the condenser electronic fan operates normally.

Second listen: after the air conditioner is running

It is abnormal to hear that the oil has no noise and impact sound when the compressor is running.

Listen to whether there is noise in the operation of evaporator blower, condenser electronic fan, motor, etc., and it is abnormal.

Three touch: after air conditioning operation

Touch the high and low pressure pipes of the refrigeration system. It is normal that the high pressure pipes are hot and the low pressure pipes are cold.

The heat of the condenser is normal, and the temperature difference between the condenser from bottom to top is the normal temperature of the dry filter, and there is no obvious temperature difference between the inlet and outlet is normal.

It is normal that there should be a significant temperature difference before and after the expansion valve.

It is normal for the air from the air supply outlet in the vehicle to feel cool.

Four measurements: after the air conditioner runs

1. Leak detection with leak detector

Use a leak detector to check whether there is leakage at all joints of the whole system.

2. Check with Multimeter

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

3. Check with thermometer

The failure of condenser, evaporator and liquid reservoir can be judged by thermometer.

When the evaporator works normally, the lower the evaporator surface temperature is without frost, the better. When the condenser works normally, the temperature of the condenser inlet pipe is 70 ℃, and the temperature of the outlet pipe is about 50 ℃. When the reservoir works normally, the temperature of the reservoir should be about 50 ℃. If the upper and lower temperatures of the reservoir are inconsistent, it indicates that the reservoir is blocked.

4. Check with pressure gauge

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

The pressure at the high-pressure end shall be 1.421~1.470mpa, and the pressure at the low-pressure end shall be 0.147~0.196mpa. Otherwise, the air conditioning refrigeration system is faulty.