1. Compressor
First, remove the wires from the wiring terminals, totaling 3 terminals. Using a multimeter resistance range, first measure the resistance between each terminal and the metal part of the compressor body. If the resistance is found to be below 1M Ω, it can be determined that the compressor of the VRF is damaged; If not, measure the resistance of any two of the three wiring terminals. If the resistance is greater than 1K Ω, it can be judged that the compressor is damaged. If not, further judgment needs to be made based on the actual situation.
2. Oil separator
During maintenance, the main focus is to check whether the capillaries and filters are blocked or leaking. In addition, when the oil in the system deteriorates and turns black severely, it is required to replace the oil separator; Or it may need to be dismantled and repeatedly purged with nitrogen to ensure that there is no oil accumulation or impurities inside.
3. Four way valve
Valve body: First, the high and low pressure of the system can be established before reversing. At this time, the main check is whether the valve body is reversing when it is electrified. If there is electricity but no reversing, you can try to solve it by tapping the valve body lightly. If not, further inspection is needed.
Coil: Use a multimeter resistance range to test the resistance value of the coil. If it is around 1-2K Ω, it is normal. If it deviates significantly, it can be judged that the coil is damaged. During operation, the AC voltage range of the multimeter can be used to measure the voltage value of the plug-in. If it is around AC220V, the control board outputs a control signal. At this time, check that the valve body is reversing. If there is no reversing, further judgment needs to be made based on the actual situation
Two common faults:
Incomplete reversing of the four-way valve: The internal slider of the four-way valve is in the middle state, causing all four connecting pipes of the four-way valve to be connected to each other. The phenomenon exhibited by the machine is high pressure low, low pressure high, and no heating effect during heating.
The four-way valve does not change direction: the possible reason is that the pilot valve body is damaged; The motherboard did not provide the correct signal; The capillary tube on the valve body is flattened. Commonly used in heating, judged by touching the pipeline. Normally, it should be the low temperature of the outdoor heat exchanger, and the pipeline connected to the indoor is in a high temperature state
4. Electronic expansion valve
The electronic expansion valve component consists of a coil and a valve body. When it comes to maintenance, the valve body and coil need to be clamped in place. When it comes to valve body replacement, the valve body needs to be wrapped with a damp cloth and quickly cooled with water after welding. During the maintenance process, valve bodies of different models and brands cannot be replaced arbitrarily.
A simple method to determine if the valve body is in motion is that during initial power on, the valve body undergoes a closing process, which can be determined by touching the valve body with your hands and listening to the sound of "da da da" to determine if the valve body is in motion.
5. Low pressure tank
For refrigeration system faults, the low-pressure tank can play a crucial role in locating the fault. When water or impurities enter the system, they will be stored in the low-pressure tank; When the compressor fails due to poor oil return, it is common for the low-pressure tank return oil hole to be blocked.
When it comes to systems with oil spoilage, conventional cleaning methods cannot blow the oil clean. It is generally recommended to replace the low-pressure tank.
When the on-site demand is urgent and the cause of the malfunction can be determined, a hole can be drilled at the bottom of the compressor to discharge the oil, then cleaned with nitrogen gas and welded back to the opening.