First, the air conditioning system of mechanical failureAir-conditioning system of mechanical failure include compressor failure, a condenser and fan failure, blowers fault, Drier, expansion valve and evaporator fault fault. Determine whether the compressor drive belt failure depends on whether the aging, cracked, loose or too tight, the impact of power transmission. Internal parts damaged or worn, the impact compression performance, the performance of the compressor abnormal noise. Compressor cylinder head gasket blow-by gas, into the exhaust valve damage, the impact compression performance.Condenser and fan failure mainly to see whether the fins are covered with grease, dust, impact of heat. Fan is running well. Blower failure depends on functioning properly, it may lead to insufficient air stream. Drier look at the screen and contains desiccant. Filter is blocked, which may affect the refrigerant flow; desiccant whether the failure, affecting the water absorption capacity may cause ice block. Normal desiccant is blue, the desiccant is saturated with water red. Expansion valve failure depends on the port through the expansion valve to control the opening and closing of the refrigerant into the evaporator liquid flow, the regulating the cooling capacity. If the valve port is always open is too large, a large amount of refrigerant flowing into the evaporator surface due to cold frost, resulting in refrigeration for a long time to stop; if the valve port is always open is too small, the refrigerant flows into a small amount, resulting in insufficient cooling. Evaporator fins depends on whether oil, dust cover, the impact of the heat exchange; whether deformation.

Second, the air conditioning system of electrical circuit faultPressure sensors, temperature sensors, thermostat, compressor electromagnetic clutch, high and low pressure protection switch, expansion valve bulb and so on.Third, the refrigerant and refrigerant oil caused by the failureFailure refrigerant and refrigerant oil caused by many reasons, including lack of refrigerant caused by excessive cooling, refrigerant shortage caused by too little refrigerant, the refrigerant and the refrigerating machine oil contains too many impurities, caused by lack of micro-blocking cooling capacity, air conditioning and refrigeration the system has water infiltration caused by lack of refrigeration, air in the system lead to inadequate cooling and low-quality frozen oil shortage caused by refrigeration.If the refrigerant is excessive, slow heat dissipation. If too much maintenance refrigerator oils, but also make the cooling system of heat dissipation decreases. Repair Methods: viewed from above the drying tank sight glass. If the car air conditioner in operation sight glass is not visible from a little bubble, no bubble after a compressor stall, it is certainly too much refrigerant. If the excessive amount of oil added to the refrigeration, air-conditioning system when the normal operation, from the sight glass bubbles see more cloudy. If indeed excessive cooling agent, can repair the air conditioning system at the mouth of the low pressure side slowly to release some of the can.Most causes refrigerant shortage is due to the system's refrigerant leak trace. Inspection Methods: shortage of refrigerant can be seen from the top of the sight glass in the drying tank, in the normal operation of air conditioning, if sight glass in continuous slow bubbles, the refrigerant shortage. If the apparent reversal of air bubbles appear, there is a serious shortage of refrigerant refrigerant and refrigerator oil contains too many impurities, slightly less cooling capacity caused by blocking. Often called dirty block: filter drier filter, expansion valve, condenser, evaporator, high and low pressure pipe.When aqueous refrigerant through the expansion valve orifice, the temperature dropped, the water molecules in the pores of freezing phenomenon and led to the refrigerant flow is not smooth, the resistance increases, or completely immobile. This phenomenon is called ice block. Repair Methods: Stop for a while, until the ice melted, the refrigeration system will appear a normal state. This is to confirm the presence or absence of water systems in important ways.Difficult to compress into liquefied air gases, into the air can cause the compressor discharge pressure and exhaust gas temperature increases in the cooling system, resulting in decreased output of cooling capacity. Cooling system sealing deteriorates, or service is not completely evacuated. With poor quality frozen oil refrigerant cycle will be deposited in the condenser and evaporator surface, the impact of air conditioning system pressure is too big reason heat exchange with the system mixed with air: let go of the refrigerant, vacuum, excessive refrigerant: release the excess refrigerant condenser cooling bad: fins clogged or heat well, need to improve the cooling conditions, high pressure switch bad work.