What details should we pay attention to when repairing refrigerators

What details should we pay attention to when repairing refrigerators

A. Starting with the test machine, it is recommended that the machine which can start and run normally should stop for more than one hour. When the process pipe is opened in a short time, no refrigerant will be ejected. Especially the machine which uses 600A refrigerant. Why? Refrigerant is compressed at high pressure (condenser. door-sealed dew-proof tube) and evaporates slowly to low-pressure evaporator, so the high and low pressure of shutdown need a certain time of neutralization pressure. Pipe cutting maintenance usually takes more than 5 minutes to shut down, so as to facilitate the preliminary determination of the amount of refrigerant in the machine.

B. Of course, all kinds of blockage mechanisms, such as dirty blockage, shutdown time is longer, the refrigerant in the cut process tube has not been discharged or even inhaled, so the high pressure tube must be cut before the refrigerant can be ejected.

C. The formation of ice jam usually comes from refrigerant, which is brought in when pressing, inhaled after leaking, the water content of compressor oil and gas-liquid separating bottle can not be eliminated, and the system has been exposed for too long time, the wet air is pressed immediately after the machine test of refrigerant has not completely leaked, the air is pumped out badly, the filter is not good, etc. The control of ice jam should be cured. It is not advocated to add methanol to cure the root cause.

D. Capillaries generally advocate the original machine, so as to maintain the aperture and length. Throttle, some of the capillaries purchased now are very poor, and they break off after a few flicks. However, it is not realistic to dig the original outer cloth pipe. If the length and diameter of the newly laid evaporator tube are changed, then the length and aperture of the capillary tube will not be changed. If you can refer to the original machine completely, the capillary is too long, the high pressure is too high, and the low pressure is too low, if the reference pressure gauge pointer maintenance colleagues will continue to add refrigerants, shutdown and reopening the compressor will inevitably protect, and vice versa, inaccurate throttling will cause poor refrigeration effect.

E. In this section, it is often found that the effect can not be achieved after the same kind of pipe laying. The pipe laying must reach an effective length in the box. The pipe laying does not advocate laying evaporators on six large and thin copper pipes. Although the cost of the pipe laying is relatively low and the pipe laying is good, the performance has changed a lot, so why not good manufacturers lay pipes like this? The pipe laying must be required. The duct is close to the inner liner, so that the pressure is obvious, the refrigeration can be effectively endothermic; the refrigerator evaporator pipeline should be avoided or kept at a certain interval with the sewer, otherwise the sewer pipe will be easily frozen and blocked.

F. Just contact refrigeration product maintenance, it is recommended to use nitrogen, pressure and flushing pipeline when pressure, speed, performance. The effect of air can not be compared with it, used will know, of course, after experience can not be used, no nitrogen humidity overweight can be replaced by R22 high-pressure refrigeration gas.

G. At the same time, heating compressor (oxygen welding) and inner box (hairdryer or light bulb) can be used to make sure that there is no air leakage between the pumping pipes during the pumping process, which will result in ineffective pumping.

H. Every time new pipelines and welded joints are laid, the old pipelines should be installed or even flushed red by high pressure gas flushing, especially before and after the welding head of the filter should be flushed once to prevent dirty blockage (half blockage). Before the installation of the filter, there is no need to burn red to remove water, which often results in excessive oxide scales. The bend around the pipeline should not be too flat, so as to avoid secondary throttling, low pressure and abnormal, resulting in misjudgement;

I. Before welding pipeline, each small contact pipe should extend into the large pipeline about 1 centimeter. If it is too short, welding blockage (half blockage) will easily occur.

J. Refrigerant can also be added into the fixed bottle, measuring the current, looking at the condensation of the return pipe, etc. Refrigerant is insufficient, and it takes a long time to test the machine under the normal condition of the temperature controller, and it is difficult to stop the machine (3 hours). The frost connection of the evaporator plate in the refrigeration room of the freezing test machine is unsatisfactory. Refrigerant leakage is caused by the long time opening opportunity. Refrigeration chamber or freezing chamber knot is transparent and hard ice, which has no effect at all. Refrigerant addition is too much, and there will be frost hanging on the return pipe (frosting). If refrigerant is added too much, the refrigerant can not evaporate sufficiently, which will also lead to insufficient refrigeration in the box. If refrigerant is not enough, it can be added directly, so refrigerant can be added directly. More according to the pressure gauge is positive or negative pressure, positive pressure can be directly discharged for a few seconds, and then open for about 10 minutes to see whether the return trachea defrost, if it is negative pressure can stop and wait for positive pressure after discharging, but this delay, directly off the machine can be pumped by vacuum pump for a few seconds, which is also good.

K. Seals generally start-up, because the start-up pressure is low close to atmospheric pressure, in the welding process, because the sealing clamp is not sealed properly, the refrigerant spray welding is not strong.

L. Test time is usually strong cold in summer (adjusted to the maximum) within 3 hours without freezing, back to the minimum (1). If the shutdown, and the cold condensation of the air return pipe is normal, 1.5 hours in winter can be used, in summer to shorten the test time can be used blower or air conditioning to reduce the test time.

M. The evaporator material can be detected by strong magnet inner gallbladder.

N. Find out where the capillary outlet can be fluorinated to see where to refrigerate first.

O. To determine the exhaust performance of compressors, high and low pressure pipelines are usually welded, and power is blocked by fingers for several seconds, so it is better not to be blocked.

P. Another way to determine the exhaust performance of compressors is to install a pressure gauge of 2.5 on the high-pressure exhaust. If the pressure gauge can't rise above 2.5 or 2.5 after the shutdown, the pointer will rebound to zero immediately after the shutdown, which proves that the compressor crossflow cannot be maintained.

Q. There is a kind of refrigerator failure. When the compressor has not been dumped and oiled, the oil is intermittently ejected from high pressure. At this time, the compressor problem should be considered.

R. Some compressors found that they could not start