Summary and analysis of air conditioning maintenance methods

Common fault phenomena:

1. leakage: refers to leakage caused by refrigerant leakage or insulation damage of power supply wire.

2. card: refers to the phenomenon of fan bearing jamming, compressor internal jamming, four-way valve body jamming and other transport parts.

3. plugging: refers to the dirty plug and ice plug of the refrigeration system; the dirty blockage of condenser and evaporator; the air inlet and outlet are blocked by obstacles, etc.

4. burn: refers to the burning of fan motor motor coil, internal winding of compressor, and burning of four-way valve coil and solenoid valve coil.

5. damage: fan blade is broken and various parts are damaged.

6. break: fuse is blown; contact of overload protector is disconnected due to overheating or excessive current; power wire is disconnected; contact of pressure relay is disconnected due to abnormal pressure of refrigeration system.

Judgment method

The basic method to judge the common faults of air conditioner is to look, listen, touch, measure and analyze.

1. See: carefully observe the working conditions of all components of air conditioner, focus on the three parts of electrical system, refrigeration system and ventilation system to judge whether they work normally.

(1) Electrical system: first, check whether the electrical connection is in good contact and loose; whether the power supply voltage is in the normal range, observe whether the fuse of the electrical system is blown, whether the insulation of the electrical conductor is intact and whether there is any burning mark on the circuit board.

(2) Refrigeration system: observe whether the pipelines of the refrigeration system have frost, condensation and ice, etc.; whether there is any damage or oil contamination at the connection between the refrigeration pipelines. In particular, there is no leakage at the joint of the refrigerant pipeline and the joint. There will be oil pollution at any leak, and soapy water can be applied to oil contaminated areas to check whether there is any foam to judge whether there is any leakage.

(3) Ventilation system: whether the fan and fan blades are running normally; whether the air inlet and outlet are smooth: observe whether the filter screen of the inner machine is dirty or blocked, whether the evaporator of the inner machine and the condensation fins of the external unit accumulate too much dust; whether the wind force is normal, etc.

2. Listen: power on and start carefully to hear whether the fan is noisy or not, whether the noise is too large; whether the air conditioner compressor is running normally, whether there is abnormal sound, etc. If the vibration and noise are too high, the possible causes are:

(1) improper installation: for example, the size of the support does not match with the unit, fixed or not, or damping rubber, foam plastic pad, etc., which can make the air conditioner vibrate and noise increase when it is running. Especially when it is just started and stopped, it is most obvious.

(2) Abnormal sound of fan: the fan blade may be impacted by poor installation or deformation, and the fan may collide with the wall shell and chassis, the axial movement of the fan will move, and the blade will also produce impact sound when the blade is unbalanced; if there is foreign matter in the fan, the impact sound will occur when the blade collides with it.

(3) Abnormal noise of compressor: shock pad at the installation position of compressor is damaged; refrigerant problem; compressor cylinder is stuck, etc

3. Touch: touch the air conditioner with hand to feel the cold and hot, vibration and other conditions, which is helpful to judge the nature and position of the fault. Normally, the temperature of condenser is gradually decreasing from top to bottom, and the temperature at the lower part is slightly higher than the ambient temperature. If the whole condenser is not hot or the upper part is slightly warm, or the temperature of the two adjacent pipes is obviously different although the heat is relatively hot, it is abnormal. Under normal conditions, the evaporator will have cold feeling and condensation when the palm is placed on the surface of evaporator. The capillary at the dryer and outlet shall have a temperature and heat sense under normal conditions (slightly higher than the ambient temperature, basically the same as the temperature of the pipe at the end of the condenser). If it is found that the temperature is lower than the ambient temperature or the surface has dew condensation and the temperature difference in each section of the capillary is abnormal. In normal cases, the temperature shall be the same as the ambient temperature.

4. Measurement: in order to accurately judge the nature and position of the fault, pressure gauge and multimeter are often required to check and measure the performance parameters and status of air conditioner. If the pressure gauge is used to check whether the system has refrigerant leakage; use multimeter to measure whether the power supply voltage, the voltage to ground of each terminal and the running current meet the requirements. The air conditioner controlled by the computer shall also measure whether the potential of each control point is normal, etc.