Reasons for low pressure alarm of chiller:
1. The copper pipe of the air conditioning refrigeration system is too long
During the debugging process, the low-pressure alarm time set by some air conditioners is relatively low (generally 120 seconds); when the copper pipe of the air conditioner being debugged 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 filter of the air conditioner indoor unit 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 filter of the air conditioner indoor unit.
3. The dry filter is dirty and blocked or the copper pipe is blocked by oil
Copper pipe connections require welding. Some copper slag cannot be completely cleaned by blowing. The dirt in the refrigeration system will accumulate in the dry filter. During the operation of the air conditioning refrigeration system, there will be a temperature difference between the two ends of the filter.
Solution: If the filter is particularly dirty, the refrigeration system needs to be blown out or cleaned again. The general solution is to replace the dry filter with the same model and specification.
4. Low-pressure protector failure in air-conditioning refrigeration system
We carry out meter testing on 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 return liquid pipe in the air-conditioning refrigeration system is flattened, resulting in unsmooth 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 position of the flattened copper pipe and replace the copper pipe of the same specification.
6. The solenoid valve in the air-conditioning refrigeration system cannot be opened
When the refrigeration system is running, the sound of the solenoid valve opening can be heard; 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 that the coil has been burned.
Solution: Replace the solenoid valve coil with the same specification and model
7. Expansion valve failure in air conditioning refrigeration system
If the expansion valve fails, when the refrigeration system is running, the low pressure cannot be increased, the high pressure cannot be increased, and the low pressure cannot be increased by adding refrigerant.
Solution: First adjust the opening degree of the expansion valve. If it still does not work, 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 iced).
8. Refrigerant leakage in air conditioning refrigeration system
First, hang a meter to test the air conditioning refrigeration system. Once the meter is hung, there is no pressure display, indicating that the refrigerant in the refrigeration system has leaked out; if there is still pressure at this time, the refrigeration system can barely run, and the pressure immediately rises when adding refrigerant, which also indicates that the refrigerant is leaking.
Solution: First, test each position of the refrigeration system to see if there are 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 and repair the leak, and re-debug the refrigeration system.
9. The cooling effect of the condenser of the air conditioning refrigeration system is too good
It mainly occurs when the ambient temperature is low, such as in winter. We often see that some cooling tower equipment has to turn off the fan in winter 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.
