The refrigerator door light is on, but what is the reason why the compressor doesn't work? How to check?
A, check the external power supply and compressor input voltage.
Check whether the input voltage of power supply and compressor meets the standard requirements (187V ~ 242V). Check whether the input voltage of external power supply and compressor is within this range with multimeter AC gear. If not, take measures to adjust it to the normal range.
Second, the ambient temperature is too low.
A. When the ambient temperature is too low (1 ~ 10℃), if the refrigerator is in manual compensation mode, it is necessary to turn on the compensation switch at this time. If the magnetic control temperature compensation switch is used, it is necessary to check whether the magnetic control switch is normal: because the ambient temperature is too low, especially for the refrigerator with double temperature and single control, as long as the compressor works for a short time, the refrigerating room will reach the predetermined temperature (/kloc-.
At the same time, due to the low ambient temperature, the temperature of the refrigerating room rises slowly or does not rise, the compressor does not work for a long time, and the shutdown time is too long, resulting in the high temperature of the freezing room, which cannot reach below-18℃.
B. When the ambient temperature is lower than 0℃, the refrigerator should be stopped: because when the ambient temperature is lower than 0℃, the compressor oil thickens and the lubrication performance becomes poor; At the same time, the condensation pressure becomes lower and the refrigerant will not flow into the evaporator. At this time, if you continue to use the refrigerator, it will not work normally and the compressor may be damaged.
Third, check whether the thermostat or the main control board is normal.
A. First, check whether the thermostat is in the "0" position; If it is not in this position, then check whether the thermostat is normal: when power is on, set the thermostat in the strong cold position (if there is no strong cold position, set it in the No.7 position). If the temperature probe is in the box, you can also use a hot towel to heat the temperature probe of the thermostat and observe whether the compressor is running.
If the compressor does not start, the thermostat may be faulty. At this time, cut off the power supply, remove the thermostat, and measure whether the power supply contact and the compressor input contact are connected (the resistance value is zero, and the corresponding contact can be measured according to the thermostat model and parameter plate). If it is turned on, check whether the temperature sensing tube of the thermostat is damaged, cracked and leaked. If so, the thermostat needs to be replaced.
B. For the refrigerator with electronic control system, measure whether the input voltage and output voltage of the main control board are normal or not with the multimeter AC voltage block in the electrified state, and whether the display screen shows that the compressor is working. Is the sensor normal? Is the connector in normal contact? If the input terminal voltage is normal and there is no voltage at the output, it means that the main control board is faulty.
Fourthly, the PTC starter fails.
Use an ohmmeter to measure whether the resistance values at both ends of the running jack and the starting jack of the PTC starter are normal (normally, the normal resistance values are between 16 ~ 50 ohms). If it is infinite or 0, the PTC starter is damaged and should be replaced.
Five, overload protector failure
Use an ammeter to measure whether the starting and running current of the compressor is normal (the starting current is generally about 5 ~ 8 times of the running current). If the current is normal, the overload protector will fail and should be replaced. Otherwise, the compressor is faulty.
Six, compressor connection point contact is good?
Check the connection of PTC start protector of compressor, and reconnect it for power-on test.
Seven, compressor internal fault
If all accessories of the compressor are normal, but the compressor still can't be started, and the overload protector acts (at this time, the starting current is measured to be too large), it is judged that the compressor is stuck in the cylinder or locked in the shaft, and the compressor needs to be replaced.
Eight, compressor winding short circuit
Measure the resistance of the three terminals with an ohmmeter. If the resistance of one terminal is zero or infinite, it means that the winding is short-circuited or open-circuited, and the compressor needs to be replaced.
Other factors that cause the compressor to fail to start:
(1) Turn-to-turn short circuit of compressor motor.
(2) Bad temperature controller.
(3) The overload protector is defective.
(4) The starting relay is damaged. First, measure the resistance of the compressor motor with a multimeter, and then check whether the thermostat is in good condition and the overload protector is normal. It is estimated that the starting relay is damaged internally. Try to connect the starting end and the running end with insulated wires, the fault disappears, and it is judged that the starting relay is damaged.
Troubleshooting: After replacing the starting relay, troubleshoot.
Extended data
Refrigerator is a kind of refrigeration equipment to keep a constant low temperature, and it is also a civilian product to keep food or other items at a constant low temperature. There are compressors, ice makers, cabinets or boxes for refrigeration, and there are storage boxes with refrigeration devices in the boxes. The volume of domestic refrigerators is usually 20 ~ 500 liters. 19 10 the world's first compressed refrigeration household refrigerator came out in the United States.
1925 Lido Company of Sweden has developed a household absorption refrigerator. 1927 the general electric company of the United States has developed a fully enclosed refrigerator. 1930, air-cooled continuous diffusion absorption refrigerators with different heating methods were put on the market. 193 1 year, a new refrigerant freon 12 was successfully developed. Domestic thermoelectric refrigerators began to be produced in the second half of 1950s, and refrigerators began to be produced in China in 1950s.
Fault checking method
look
By observing the surface phenomenon of refrigerator in work, the fault symptoms are analyzed.
① Observe the frosting on the evaporator surface. If the frost on the evaporator surface is uneven or incomplete, it means that the refrigerant in the refrigeration system is insufficient and there is a leak. If the frost layer on the evaporator surface is too thick, defrost it in time or reset the defrosting time.
② Look at the cooling speed of the freezer. If the refrigeration speed is obviously lower than the original normal operation speed, it is caused by the lax closing of the refrigerator door (aging or damage of the magnetic sealing strip), insufficient refrigerant in the refrigeration system, too much dust on the condenser surface or too thick frost on the evaporator surface. All these will make the compressor work for a long time and the temperature drop slowly.
③ Check the external surface of the refrigeration system (especially the surface of the joint and evaporator). If there is oil stain on the outer surface of the refrigeration system, it means that there is leakage, which will lead to the decrease of refrigeration capacity, uneven or incomplete frost on the evaporator surface, and even the refrigeration system completely loses its refrigeration capacity.
④ Check the suction line on the compressor. If there is frost or dew on the gas pipeline, it may be that the refrigerant is charged too much, or the frost layer of the evaporator is too thick, resulting in poor evaporation of refrigerant liquid in the evaporator, and it reaches the suction pipeline to further absorb heat, evaporate, frost and dew. Severe frosting and condensation may occur on the compressor.
listen to
Listen to the operation of the refrigerator after it is electrified, such as whether the motor is running, all kinds of sounds when the compressor is working, and whether the air flow sound in the evaporator is abnormal.
(1) Listen to the noise during compressor operation. When the power supply is turned on and the "beep" sound of the starting relay is heard, the compressor motor can be started in 0.2 ~ 0.5 s, and there is no abnormal noise during the operation of the compressor, indicating that the compressor and motor are in good working condition.
If the compressor makes a "buzzing" sound when starting, and at the same time, the contact of the starting relay jumps, and the repeated "beep" sound of inhalation is accompanied by the violent shaking sound of the compressor, it means that the compressor is not running and there is a serious fault. This is caused by short circuit, open circuit of motor winding, mechanical failure of compressor, failure of starting relay and blockage of pipeline at high pressure end of refrigeration system, which makes the compressor load too large.
When the compressor is running, if you hear a "click" sound, it is a metal impact sound coming from the inside of the compressor, indicating that the internal moving parts are loose, causing the parts to collide with each other.
If the compressor is in operation, it hears the hissing sound of air flow, which is because the exhaust buffer pipe of the compressor falls off or breaks, thus giving off the high-pressure air flow sound; If the compressor stops working, you can hear the obvious "hissing" sound of rubber ball deflation, then the high and low pressure gaskets on the valve plate of the compressor are punctured, or the suction and exhaust valves are not tight or damaged, resulting in the sound of air flow from the high pressure end to the low pressure end.
If the compressor makes abnormal noise when it is running or stopping working, it is caused by the fracture or fatigue deformation of the supporting suspension spring in the compressor.
② Listen to the sound of refrigerant in the evaporator. When the refrigeration system works normally, the slight continuous "hissing" throttling sound of refrigerant entering the evaporator through the capillary tube and the slight boiling and vaporization sound of boiling water in the evaporator can be heard, which indicates that the refrigeration system works normally.
If you can hear a slight creaking sound in the evaporator, intermittent refrigerant throttling sound and slight suction sound when boiling, it is because there is a small amount of water in the refrigeration system, resulting in intermittent ice jam at the capillary outlet.
If you can hear the sound of air flow in the evaporator, it means that the refrigerant in the refrigeration system basically leaks light; If you can't hear the sound of air flowing in the evaporator, it is that the refrigeration system is blocked or there is no refrigerant in the refrigeration system and it has leaked clean.
(3) Listen to the sound when the refrigeration system is working. When the refrigeration system works normally, you can hear the sound of running water in the system pipeline. If you can't hear any noise from the condenser, but sometimes you can hear the "ice crack" sound in the refrigerator when you stop working, that's normal.
If the evaporator surface temperature drops to about -20* (2) When the refrigeration system is working, the condenser will have a large abnormal sound, which will be high and low, and the suction sound will be very stable when it is blocked. At the same time, it is sometimes heard that the suction pipe is accompanied by vibration, which is due to the addition of different specifications and models of refrigeration oil or the poor quality of refrigeration oil, which will lead to wax deposition and oil blockage in the capillary.
(4) Listen to the overall sound of the refrigerator. ~ a good refrigerator can't make any abnormal noise when working. If abnormal noise occurs in the use of the refrigerator, it is mainly due to unstable installation of the refrigerator and loose fastening screws, which leads to vibration of the refrigeration pipeline. If the grid in the refrigerator box is not flat, it will cause the storage items to be placed unsteadily and collide with the inner wall of the refrigerator to produce noise, which can be eliminated by taking corresponding measures.
touch control
Touch the temperature changes of each part of the refrigerator refrigeration system with your hands to judge and analyze whether the refrigerator works normally and where the fault lies.
(1) Touch the operating temperature of the compressor. See Table 4- 10 for the compressor shell temperature. Generally, when the indoor ambient temperature is lower than 30 "C, it is normal to touch the surface temperature of compressor shell with your hands, but you can keep your hands on it. If the compressor shell temperature exceeds 80℃. C, you can't keep your hands on it all the time. It's very hot. At this time, the compressor discharge temperature can reach 130. C. If there is no fault in the compressor and the refrigerant charge is appropriate, it means that there is too much dirt in the condenser or the ventilation and heat dissipation are not good.
If the compressor has been working for a period of time and the temperature of the compressor shell is cold or close to the temperature of the human body, it means that there is no refrigerant in the refrigeration system. If the refrigeration system lacks refrigerant or the heat load increases, the compressor temperature will be too high.
② Touch the surface temperature of condenser and exhaust pipe.
If the outer surface temperature of the first three or four tubes contacting the surface of the condenser is high, the outer surface temperature of the last tube is lower than that of the first few tubes, which is close to the indoor ambient temperature or has a warm feeling, indicating that the condenser works normally; If the whole condenser pipeline heats up, it means that the refrigerant in the refrigeration system is charged too much or there is air in the refrigeration system.
B. Touch the surface of the exhaust pipe by hand. Under normal working conditions, the external surface temperature of the exhaust pipe is high, and it is hot in summer and hot in winter; If there is no temperature, there is no refrigerant in the refrigeration system
③ Touch the surface temperature of drying filter and capillary. Under normal working conditions, the surface temperature of the drying filter and capillary should be close to the indoor ambient temperature, and it will feel a little warm when touching the outer surface with hands. There should be no obvious temperature difference before and after touching the drying filter and capillary. If there is a temperature difference or lower than the ambient temperature, there is frost and dew, indicating that the mesh in the drying filter has been blocked or the capillary is blocked.
④ Touch the evaporator surface. When the refrigeration system works normally around 15 ~ 20 rain, the evaporator surface should be covered with a uniform layer of solid frost. When touching with fingers in water, there is obvious sticky feeling, which shows that the refrigeration effect is very good. If you touch the surface of the evaporator and the frost falls off, it is virtual frost, and then touch the suction pipe, it is that the refrigeration system is filled with too much refrigerant; If the frost on the evaporator surface is uneven, or the first half
Frost on the edge and dew on the back half indicate that the refrigeration system is not filled with enough refrigerant, or the capillary and drying filter are blocked; If there is condensation or no condensation or frost on the evaporator surface, it means that the refrigerant in the refrigeration system has basically leaked out or the refrigeration system is seriously blocked.
⑤ Touch the external surfaces of components, pipes, interfaces and welding heads in the refrigeration system. Under normal circumstances, these external surfaces should be free of oil stains. If there is oil stain on the touch part, it means that there is leakage in this part.
quantity
By measuring the operating voltage, working current, temperature and pressure of the refrigerator with instruments and tools, the fault position can be judged and analyzed, which further proves the accuracy of seeing, listening and touching, and has the practical effect of getting twice the result with half the effort.
① Measure the working voltage and current of the refrigerator.
Using multimeter to measure the working voltage of refrigerator should be within the calibration range of (220LO%) V. It is worth noting that although all brands of refrigerators have given the requirements of working voltage range, the failure rate will increase correspondingly if the refrigerator works at the highest or lowest edge of the required range of power supply voltage for a long time, which is the most likely to damage the electrical components in the refrigerator, especially the compressor motor.
When measuring the working current of refrigerator with clamp ammeter, it should not exceed the rated current of nameplate. If it exceeds or approaches the rated current of the nameplate, there will be serious hidden dangers to the normal use of the refrigerator.
A. measure the starting current of the compressor. The normal start-up current of the compressor is about 7 ~ 8 times of the rated current, and the start-up work is completed in 0.2 ~ 0.5 s. If the rated current of the refrigerator nameplate is 0.9 A, the normal instantaneous start-up current should be about 7 A; If the starting current reaches more than 8 A, it is too high. If the compressor starts for a long time and the starting current is too large, it indicates that there is a turn-to-turn short circuit in the starting winding, or the compressor has some faults such as shaft locking, cylinder sticking and high-pressure exhaust pipe blockage. If the starting current is too low (except PTC starting elements), when the starting current is less than four fifths of the normal starting current, the compressor cannot start normally, indicating that the compressor motor winding is open.
B. measure the working current of the compressor. If the working current of the compressor is too high, it means that there is too much refrigerant in the refrigeration system, air in the refrigeration system, too much dirt in the condenser or too much heat load. If the working current of the compressor is small, it means that the refrigeration system is short of refrigerant or the drying filter and capillary are blocked.
C. ohmic resistance of quantity control circuit. Using ohmmeter to measure the resistance of each element in the control circuit can quickly find the fault position and damaged electrical components in the circuit, and replace and repair them in time.
② Measure the pressure and temperature of the refrigeration system.
A. measure the pressure of the refrigeration system with a pressure gauge. Connect a low-pressure pressure gauge to the maintenance valve connected to the compressor charging pipe to measure the suction pressure when the compressor is running. For example, the temperature of the freezer should reach-18. C or so, if the measured suction pressure is too high, it is too much refrigerant; If the suction pressure is too low, the refrigerant is insufficient or the drying filter and capillary are blocked.
When the indoor ambient temperature is about 30℃, if a high-pressure pressure gauge can be connected to the exhaust line of the compressor, the exhaust pressure can be measured to be about 7.5 kPa/cm2. If the exhaust pressure is too high, it means that there is too much refrigerant and air in the refrigeration system or too much dirt in the condenser; If the exhaust pressure is too low, there is insufficient or no refrigerant, and the capillary of the drying filter is blocked.
B use a thermometer to measure the temperatures of all parts of the refrigeration system and the freezers and freezers. The thermometer probe is attached to the outer surface of the measured component in the refrigeration system to minimize the influence of the ambient temperature on the temperature probe, so as to judge whether the refrigeration system works normally. See Figure 4- 1 1 for the temperature of each part of the refrigeration system. Put a thermometer in the freezing and refrigerating room to actually measure whether the temperature in the freezing and refrigerating room is within the use requirements.
③ Measure the start-stop time of the compressor.
The start-stop time of compressor directly affects the use effect of refrigerator. In use, it is hoped that the shorter the running time of the compressor, the better the downtime, so as to achieve the purpose of saving electricity. When measuring the start-stop time of the compressor, you can turn the knob of the thermostat to …3' position as the measurement reference point to compare the start-stop time of the refrigerator compressor. Normal compressor start-stop time ratio: about 1: 2 ~ 1: 3 in summer and about 1: 3 ~ 1: 5 in winter.
For example, when the indoor ambient temperature is about 20℃, the compressor should run for about 10min and stop working for more than 30 min, and its start-stop ratio is 1: 3, which is normal. By measuring and comparing the start-stop time of the compressor, we can judge whether the refrigerator is in good working condition, whether the door seal of the refrigerator is tight, or whether the refrigeration system is faulty.
smell
Smell the electrical components of the refrigerator with your nose for abnormal smells, such as burning smell, to judge whether the electrical components are damaged and whether the wiring is loose. Smell the refrigerator to determine whether the items stored in the refrigerator are corrupt, and clean the refrigerator in time, especially the corrupt things in the freezer corrode the surface of the evaporator, causing the evaporator to leak. Get attention.
ask
In maintenance, it is necessary to know how to use the refrigerator, what items are stored, when and under what circumstances the refrigerator fails, and further analyze whether the refrigerator fails because of improper use or other reasons, so as to eliminate the external factors that lead to the failure, which is conducive to eliminating the refrigerator failure as soon as possible.
Second, the compressor
Compressor is a fluid machine that converts low-pressure gas into high-pressure gas, and it is the heart of refrigeration system. It sucks in low-temperature and low-pressure refrigerant gas from the suction pipe, drives the piston to compress it through the operation of the motor, and then discharges the high-temperature and high-pressure refrigerant gas from the exhaust pipe to provide power for the refrigeration cycle.
So as to realize the refrigeration cycle of compression → condensation (exothermic) → expansion → evaporation (endothermic). Compressors are divided into piston compressors, screw compressors, centrifugal compressors and linear compressors. The article introduces the working principle, classification, accessories, specifications, operation requirements, production, common faults, environmental protection requirements, selection principles, installation conditions and development trends of compressors.
Insufficient exhaust volume
Insufficient air displacement is one of the most common faults of compressor, which is mainly caused by the following reasons:
1. air intake filter failure: dirt and blockage, reducing exhaust volume; The suction pipe is too long and the pipe diameter is too small, which leads to the increase of suction resistance and affects the gas volume. Clean the filter regularly.
2. The decrease of compressor speed reduces the air displacement: the air compressor is not used properly, because the air displacement of the air compressor is designed according to a certain altitude, suction temperature and humidity. When used on the plateau exceeding the above standards, the suction pressure drops, etc. , the displacement is bound to decrease.
3. The cylinder, piston and piston ring are seriously out of tolerance, which increases the gap and leakage and affects the displacement. In case of normal wear, wear parts, such as piston rings, should be replaced in time. If the installation is incorrect and the gap is not left in time, it should be corrected according to the drawings. If there are no drawings, you can take empirical data. For the clearance between the piston and the cylinder along the circumference, if the piston is cast iron, the clearance value is 0.06/100 ~ 0.09/100 of the cylinder diameter; For aluminum alloy piston, the clearance is 0.12/100 ~ 0.18/100 of the gas diameter; Steel piston can take the smaller value of aluminum alloy piston.
4. The stuffing box is lax, causing air leakage and reducing the air volume. The first reason is that the stuffing box itself does not meet the requirements when it is manufactured; Secondly, it may be because the piston rod is not well aligned with the center of the stuffing box during installation, resulting in wear and strain, leading to air leakage; Generally, the stuffing box is filled with lubricating oil, which can play the role of lubrication, sealing and cooling.
5. Influence of compressor suction and exhaust valve faults on displacement. Metal fragments or other sundries fall between the valve seat and the valve plate of the gas valve, resulting in lax closure and air leakage. This not only affects the displacement, but also affects the change of pressure and temperature between stages; This problem may be caused by manufacturing quality problems, such as warping of valve plate, serious wear of valve seat and valve plate leading to air leakage.
6. The spring force and pneumatic force of the air valve are not well matched. Too strong elasticity makes the valve plate open slowly, and too weak elasticity makes the valve plate close untimely, which not only affects the gas flow, but also affects the increase of power and the life of the valve plate and spring. At the same time, it will also affect the changes of gas pressure and temperature.
7. The compression force of the compression valve is incorrect. If the pressing force is small, it will leak, but if it is too tight, it will not work, and the valve cover will be deformed and damaged. Generally, the following formula can be used to calculate the compression force: p=kπ/4 D2P2, d is the diameter of the valve cavity, P2 is the maximum gas pressure, and k is a value greater than 1, which is generally 1.5 ~ 2.5, and k = 65438+ at low pressure. If the air valve fails, the valve cover will be heated and the pressure will be abnormal.
Baidu Encyclopedia: Refrigerator, Baidu Encyclopedia: Compressor