Warm prompt: The overload protector is usually installed inside the compressor wiring box, with its open end tightly attached to the compressor shell to sense the temperature of the shell. In addition, the thermal element is connected in series with the circuit, and changes in current can be reflected by the increase in temperature of the thermal element, thus it can also sense the increase in current. The bimetallic strip in the protector is fixed with an adjusting screw. There is a moving contact on the bimetallic strip, while the stationary contact is connected via a terminal. When the power is turned on, if the motor cannot operate normally and there is excessive current, the thermal element will heat up due to the large current, radiating heat to the bimetallic strip, causing it to bend upward and pull the moving contact away from the stationary contact, cutting off the circuit and providing protection. If the compressor shell heats up too much, it can also cause the bimetallic strip to function similarly. Common faults of the overload protector include burned-out heating elements, damaged contacts, contacts that fail to reset after opening, insulation damage in built-in protectors, and malfunctioning contacts. The causes of these faults are as follows:
(1) Power voltage is too low, below 160V;
(2) The compressor motor runs under load at low voltage for a long time;
(3) The compressor motor runs at high speed for a long time;
(4) The cooling agent passage of the compressor motor is blocked;
(5) The operating environment temperature is too high, causing oil film destruction.
Detection method: Under the condition that the overload protector does not act, use the R10 range of the multimeter to measure. Since the two terminals are conductive under normal conditions, the resistance should be zero. If the resistance is infinitely large, it indicates that the internal contacts of the overload protector are open-circuit. Note: Some repair personnel, when the overload protector is faulty, adopt emergency handling by removing and short-circuiting the overload protector to allow the air conditioner to work normally. For such cases, a new overload protector must be replaced within a short period; otherwise, it is easy to burn out the compressor, and in severe cases, it may cause a fire, resulting in greater economic losses.
Midea Air Conditioner, Compressor Stops and Starts Intermittently
Article Source: Beijing Midea Air Conditioning Repair Phone http://blog.sina.com.cn/meidikongtiao.
Repair Method: Replace the overload protector to eliminate the fault.
Analysis and Detection: Measure the power supply voltage to be normal; disconnect the power, remove the front panel of the air conditioner, pull out the core, and measure the charging and discharging process of the compressor start capacitor to be normal; measure the overload protector to be open-circuit.