The common reasons for low pressure failure of air conditioners are as follows:
1. The copper pipe of the air conditioning refrigeration system is too long.
2. The filter of the air conditioning indoor unit is dirty and blocked.
3. The dry filter in the air conditioning refrigeration system is dirty and blocked or the copper pipe is blocked by oil.
4. The low pressure protector in the air conditioning refrigeration system is faulty.
5. The solenoid valve in the air conditioning refrigeration system cannot be opened.
6. The expansion valve in the air conditioning refrigeration system is faulty.
7. The refrigerant in the air conditioning refrigeration system leaks.
8. The heat dissipation effect of the condenser of the air conditioning refrigeration system is too good.
9. The return liquid pipe in the air conditioning refrigeration system is flattened, resulting in unsmooth return liquid.
In the final analysis, we can analyze it from the following two aspects:
01), insufficient refrigerant in the evaporator;
02), incomplete evaporation of the evaporator;
The following is an analysis of the low-pressure alarm of the air conditioner, I hope it will be helpful to you:
1. The copper pipe of the air conditioning refrigeration system is too long:
During the debugging process, some air conditioners have a relatively low low-pressure alarm time set at the factory (generally 120 seconds); when the copper pipe of the debugged air conditioner is longer, the time for the refrigerant to return to the evaporator is extended, resulting in a low-pressure alarm fault.
Solution: The low-pressure alarm time can be increased to 180 seconds. In an environment with changing weather, the low-pressure alarm time needs to be appropriately increased.
2. The indoor filter of the air conditioner is dirty and blocked:
Air circulation will adsorb dust in the environment to the surface of the air conditioner filter. Some users will ignore this problem. Day after day, the air conditioner filter is too dirty and the evaporator is frozen, resulting in a low-pressure alarm fault of the air conditioner.
Solution: Replace the indoor filter of the air conditioner.
3. The filter drier is dirty or the copper pipe is blocked by oil:
The copper pipe connection needs to be welded. Some copper slag cannot be completely cleaned by blowing. The dirt in the refrigeration system will accumulate in the filter drier. During the operation of the air conditioning refrigeration system, there will be a temperature difference at both ends of the filter.
Solution: If the filter is particularly dirty, the refrigeration system needs to be blown or cleaned again. The general treatment method is to replace the filter drier of the same model and specification.
4. Low-pressure protector failure in the air conditioning refrigeration system:
We hang a meter to test the air conditioning refrigeration system. When the pressure is normal, use a multimeter to measure the low-pressure protector circuit, or short-circuit the low-pressure protector and start the compressor. If the refrigeration cycle is normal, it means that the low-pressure protector is faulty.
Solution: Replace the low-pressure protector of the same specification and model.
5. The solenoid valve in the air conditioning refrigeration system cannot be opened:
When the refrigeration system is running, you can hear the sound of the solenoid valve opening; if the solenoid valve is not opened, the low pressure will gradually decrease until the low pressure alarm is generated; reset the alarm on the air conditioning control panel, and the low pressure will not rise. At this time, measure the solenoid valve coil. If there is a resistance value, it means it is normal, and if it is infinite, it means the coil has burned out.
Solution: Replace the solenoid valve coil of the same specification and model
6. Expansion valve failure in the air conditioning refrigeration system:
If the expansion valve fails, when the refrigeration system is running, the low pressure cannot rise, the high pressure cannot rise, and the low pressure cannot rise even if the refrigerant is added.
Solution: First adjust the opening degree of the expansion valve. If it still has no effect, you need to replace the expansion valve of the same specification and model (Note: It is necessary to rule out whether the expansion valve is dirty or ice-blocked).
7. Refrigerant leakage in the air conditioning refrigeration system:
First, check the air conditioning refrigeration system with a meter. If there is no pressure display when the meter is hung, it means that the refrigerant in the refrigeration system has leaked out; if there is still pressure at this time, the refrigeration system can barely operate, and the pressure will rise immediately after adding refrigerant, which also means that the refrigerant is leaking.
Solution: First check each position of the refrigeration system to check for signs of oil leakage, and use detergent to focus on the oil leakage position; if necessary, keep the pressure of the refrigeration system in sections, and then check it. After finding the leak, weld to repair the leak, and re-debug the refrigeration system.
8. The heat dissipation effect of the condenser of the air conditioning refrigeration system is too good:
Mainly occurs when the ambient temperature is low, such as in winter. We often see that in winter, some cooling tower equipment will turn off the fan because the condensation pressure is too low.
Solution: Increase the air conditioning start-up pressure; or modify the outdoor fan and change it to a speed-controlled fan, which can better solve the problem.
9. The return liquid pipe in the air conditioning refrigeration system is flattened, resulting in poor return liquid:
The probability of this happening is small, and the copper pipe needs to be checked to find the flattened position.
Solution: Find the location of the flattened copper pipe and replace the copper pipe of the same specification
The low pressure alarm of the air conditioner is one of the most common problems in maintenance work. The reasons for it are also multifaceted and reasonable. The above are some insights on the judgment of low pressure alarm in my work. They are for reference only. I hope they will be helpful to you.