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.

3. The dry filter is dirty and blocked or the copper pipe is blocked by oil

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

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.

7. Expansion valve failure in air conditioning refrigeration system

8. Refrigerant leakage in air conditioning refrigeration system

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

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.