Car air conditioning does not cool how to do

1. Sensory examination
(1) Check the operating state of the compressor to see if the transmission belt is broken or relaxed. If the transmission belt is too loose, it will slip, accelerate wear and cannot transmit power. In addition, check whether there is noise inside the compressor, the noise may be caused by damaged internal parts, internal wear can not be effectively compressed. Step 3 Check whether the compressor clutch is slipping.
(2) Check the condenser and fan status to see whether the condenser heat sink is covered by dust, if the condenser heat sink is covered by dust, the efficiency of the condenser will be greatly reduced. The second step is to check whether the condenser fan works well.
(3) Check the operation status of the blower fan, so that the fan operates at three speeds of "low, medium and high". If there is abnormal noise or the motor is in poor operation, it should be repaired or replaced, otherwise the air supply is insufficient.
(4) Check the amount of refrigerant liquid, if you see a large number of bubbles through the observation window, it indicates that the refrigerant is insufficient. If water is poured into the condenser to cool it, no foam can be seen in the observation window, indicating excessive refrigerant. Check whether there is oil in the joints and joints of each device. If there is oil in the joints or joints, it indicates that there is a refrigerant leak. You should re-strengthen or replace the relevant parts. (Leak detector is available)
(5) Whether the HVAC valve or thermal control windshield is closed, whether the other windshield adjustment is normal, if the compression clutch can not be drawn, the blower fan can not operate, the condenser fan can not operate, etc., should first enter the relevant electrical system check, such as relays, sensors, circuit breaks or short circuits, control units, etc.).
2, instrument detection method
This method uses a complete set of snow pressure gauges to find the fault location. First, close the high-pressure end and low-pressure end of the pressure gauge switch, in the shutdown state, connect the refrigerant filling hose to the corresponding maintenance valve of the compressor, and use the refrigerant pressure in the refrigeration device to discharge the air in the hose. At this time, the high and low pressure end reading should be in a balanced state (about 6kg/cm2) to start the engine, maintain at 150rpm, the blower speed is set at the highest level, the air conditioner is set at the maximum position, in the "recirculation" state.
(1) The indicating value of the pressure gauge on the high pressure side and the low pressure side is lower than the standard value, and bubbles can be seen through the observation hole.
Cause: air leakage in refrigeration cycle; The refrigerant is not replenished regularly.
Treatment: Use a leak detector to detect the leak, repair it, and replenish the refrigerant.
(2) The pressure gauge on the low pressure side indicates negative pressure, the high pressure side indicates a lower than normal value, there is a temperature difference between the pipes before and after the liquid storage tank/dryer, and in serious cases, there is frost in the pipes behind the liquid storage tank/dryer.
Cause: The expansion valve or low pressure line is blocked, the liquid storage tank/dryer or high pressure line is blocked; Expansion valve pressure bubble leakage, needle valve completely closed.
Treatment: Remove or replace the relevant components and liquid storage tank/dryer, if the pressure bubble leaks, replace the expansion valve.
(3) On both sides of high and low pressure, the pressure gauge indicates higher than the standard value, and the condenser discharge side is not hot.
Cause: Excessive refrigerant filling.
Treatment: Discharge excess refrigerant and make the pressure reach the standard.
(4) On both sides of the high and low pressure, the pressure gauge indicates a higher than normal value, but after the shutdown, the high pressure side pressure plummets to about 2kg/cm2.
Reason: Air is mixed in the refrigeration cycle (insufficient evacuation or air enters when filling).
Treatment: Re-pump and refill, if the above symptoms still exist, replace the liquid storage tank/dryer and compressor oil.
(5) The pressure gauges on the high and low pressure sides indicate higher than normal values, and frost or deep condensation is formed in the pipeline on the low pressure side.
Cause: expansion valve failure (needle valve opened too wide); The expansion valve pressure bubble is disconnected from the evaporator.
Treatment: Check and reconnect the pressure bubble or replace the expansion valve.
(6) The low pressure side pressure is high, the high pressure side pressure is low, and the pressure on both sides immediately tends to balance after stopping.
Cause: Compressor valve, piston or piston ring damage, can not be effectively compressed.
Solution: Replace the compressor.
(7) On both sides of low pressure and high pressure, the indicating value of the pressure gauge fluctuates.
Cause: Because the dryer is super full, the moisture in the refrigerant can not be removed, so that the needle valve in the expansion valve is frozen, causing ice blocking. When the refrigerant is no longer circulating, the ice is thawed by the turnover heat and then frozen into ice, this process is repeated.
Treatment: Replace the storage tank/dryer and compressor oil, and re-vacuum and refill.