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How to tell if it's an electrical or mechanical problem when the compressor fails?

When the air conditioner compressor fails, it's critical to tell if it's an electrical or mechanical problem. Here are some key points to make:

1. How to tell if it's an electrical problem:
The compressor won't start: When the compressor won't start at all, it could be an electrical problem, such as a power failure, capacitor failure, or relay damage.
Check the power supply: Make sure the air conditioner is receiving the proper voltage and the power cord and plug are not damaged.
Test the capacitor: Use a multimeter to check if the compressor's start capacitor or run capacitor is failing. When the capacitor is damaged, the compressor may hum but won't start.
Check the relay: If the relay is damaged, the compressor may not receive a start signal at all.
Tripping or blowing the fuse: When the compressor is short-circuited or overloaded, the electrical system will trip or blow the fuse.
Check the air conditioner circuit to determine if the compressor is short-circuited internally, causing excessive current.

2. How to tell if it's a mechanical problem:
Abnormal noise from the compressor: If the compressor makes a clicking, rubbing, or metallic knocking sound when it starts, it could be a mechanical problem, such as loose, worn, or stuck internal parts.
Bearing or piston wear: Bearings, connecting rods or pistons inside the compressor may be worn or stuck, causing abnormal noise.
Compressor overheating: If the compressor temperature is too high, it may be due to mechanical parts being stuck, insufficient internal oil lubrication, or the compressor being overloaded for a long time.
Check the lubricating oil: Insufficient lubricating oil or poor oil quality can cause internal parts to overheat and wear.
Frequent shutdowns after the compressor starts: If the compressor stops working soon after starting, it may be due to excessive internal pressure (mechanical reasons) or internal parts being damaged.
Compressor cylinder jam: Piston or other parts being stuck can cause the compressor overload protection to trip.

3. Comprehensive inspection method:
Current detection: Use an ammeter to detect the operating current of the compressor. Abnormally high current may be caused by mechanical parts being stuck, while no current flow usually points to electrical faults.
Multimeter to detect motor windings: Check whether the windings are short-circuited or open-circuited. If the resistance is abnormal, it usually means that the compressor motor is damaged.

What types of expansion valves are there in air conditioners, and how to choose the right expansion valve for replacement?

The expansion valve in the air conditioner is a key component in the refrigeration system, responsible for regulating the flow of refrigerant. There are several types of expansion valves, and different types are suitable for different systems and application environments. When choosing a suitable expansion valve for replacement, the working conditions, system type and refrigerant type of the air conditioner need to be considered.

1. Types of expansion valves
1) Thermostatic expansion valve (TXV)
Working principle: Automatically adjust the refrigerant flow according to the superheat (temperature difference) at the evaporator outlet.
Features: Accurately control the flow of refrigerant, maintain a stable superheat, and adapt to load changes.
Application scenarios: Widely used in large air-conditioning systems, refrigeration equipment and commercial air-conditioning systems, especially suitable for occasions with large load fluctuations.
2) Electronic expansion valve (EEV)
Working principle: Accurately control the refrigerant flow through electronic signals, and adjust in real time with sensors and control systems.
Features: Fast response speed, high adjustment accuracy, suitable for complex control needs.
Application scenarios: High-end air-conditioning systems, variable frequency air-conditioning or intelligent refrigeration systems, commonly used in energy-saving air-conditioning equipment.
3) Capillary Tube
Working principle: A thin tube with a fixed diameter that controls the refrigerant flow rate through a constant pressure drop and cannot be automatically adjusted according to load changes.
Features: Simple, low cost, suitable for systems with little load change.
Application scenario: Commonly used in refrigeration equipment with relatively stable loads such as small household air conditioners and refrigerators.
4) Automatic Expansion Valve (AXV)
Working principle: Adjust the refrigerant flow rate according to the pressure in the evaporator, rather than relying on temperature changes.
Features: Maintain a constant evaporation pressure, suitable for occasions with stable loads.
Application scenario: Usually used in refrigeration systems or small air conditioning equipment with constant loads.

2. How to choose a suitable expansion valve for replacement?
When choosing a suitable expansion valve, the following key factors need to be considered:

1) Refrigerant type
The expansion valve must match the refrigerant used in the air conditioning system. Different expansion valves are designed for different refrigerants, such as R22, R410A, R32, etc., so when replacing, make sure that the valve can adapt to the refrigerant of the system.
2) System load and capacity
The choice of expansion valve needs to be determined according to the capacity and load of the air conditioner. Thermostatic expansion valves and electronic expansion valves are suitable for systems with large load fluctuations, while capillary tubes and automatic expansion valves are suitable for small systems with relatively stable loads.
3) Superheat regulation requirements
If the system needs to accurately adjust the refrigerant flow and maintain a constant superheat, thermal expansion valves or electronic expansion valves are better choices. These valves can automatically adjust the refrigerant flow according to the superheat at the evaporator outlet, and are suitable for systems with large load changes.
4) Working environment
If the system works in an environment with high precision and high energy efficiency requirements (such as variable frequency air conditioners or commercial refrigeration systems), electronic expansion valves are the best choice. They can be adjusted in real time according to different working conditions and have higher accuracy.
For small household air conditioners or equipment with little load change, capillary tubes may be a better choice because of their low cost and no need for complex adjustment.
5) Ease of repair and maintenance
Thermostatic expansion valves and electronic expansion valves are more complex and require professional maintenance personnel to install and debug. Capillary tubes and automatic expansion valves are relatively easy to repair due to their simple design.
3. Summarize the selection steps
Confirm the refrigerant type: select an expansion valve that matches the refrigerant in the air conditioning system.
Evaluate the load requirements: select the appropriate type of expansion valve according to the capacity of the air conditioner and the load fluctuation.
Consider the adjustment accuracy: if the system needs to accurately control the flow and temperature, choose a thermal or electronic expansion valve.
Determine the working environment: electronic expansion valves are recommended for high-end systems or variable frequency systems, and capillary tubes can be considered for small household air conditioners.
Consider maintenance factors: select an expansion valve type that is easy to install and maintain to reduce future maintenance costs.