1, indoor machine sound.

(1) The indoor unit is in a sound state, and the uncomfortable sound in the ears is restored after the air conditioner is turned on. At this time, it is necessary to check whether the power supply voltage when the indoor fan is turned off is100V.

(2) If the indoor unit is still running slowly after being turned off, it is because the indoor motor is heated, so that the plastic motor frame is deformed after being heated, which leads to the position deviation of the plastic motor.

(3) The pleasant sound is caused by the collision between the blade and the chassis, accompanied by burning smell. It can be concluded that the fan control thyristor is damaged, and the maintenance method is to suggest replacing the main control board.

2. There is something wrong with the temperature sensor

A common fault of (1) is that the refrigeration effect of central air conditioner is worse and the wind speed is obviously lower, so it is necessary to check the thermal effect of starting mechanism before switching to air conditioner.

(2) If the adjustment of high and low wind speeds can be stopped in the form of refrigeration and air supply, and the difference between high and low wind speeds is obvious, it means that the motor of the fan is operating normally.

(3) Changing the characteristics of the indoor pipeline temperature sensor will lead to poor refrigeration effect, so the indoor pipeline sensor can be replaced.

3. Welding leakage of high pressure valve

(1) If the cooling effect of the central air conditioner is not good and the external machine leaks water, it is necessary to check the task and cooling effect of the external machine parts of the central air conditioner first.

(2) If frost is found on the evaporator in the machine, it may be because the parts are short of fluorine, and then the test is stopped and the pressure of the parts is found to be very low.

(3) This situation is usually caused by the leakage of the connecting pipe of the high-pressure valve body. The solution is to weld the high pressure valve again and then add refrigerant fluorine.

Second, Hitachi Central Air Conditioning Noise Solution

1. The main noise source of the central air conditioner is the air outlet of the central air conditioner. When the wind speed of air conditioner is turned on, the noise value of central air conditioner will gradually increase, which is one of the main noise sources of air conditioner.

2. However, if it is a central air conditioner, the indoor unit is hidden in the ceiling, and there is only a small air outlet in the visible part, which is beautiful and comfortable, and generally does not cause indoor noise problems.

3. The central air conditioner has been used for a long time, and the panel of the air conditioner is easily loosened for various reasons. In this way, the vibration generated when the air conditioner is running will make the panels rub against each other, thus generating noise.

4. The installation of indoor unit and the connection of outdoor unit of central air conditioner also affect the timing and noise of air conditioner. If the indoor unit is not installed stably enough, the copper pipe is connected to the indoor unit when the outdoor unit is running, and the indoor unit will be affected by the compressor after it is unstable enough, thus causing the indoor unit to vibrate.

5. Central air-conditioning compressor This is also one of the sources of air-conditioning noise. Excessive compressor noise will also affect the use and rest of our normal users.

Three. Causes and solutions of noise in Hitachi central air conditioning system

1, the installation process is not in place.

It is said that central air conditioning is "three points for quality and seven points for installation", which shows that the technical professionalism of workers' installation is a major factor affecting the noise of air conditioning, and the noise generated by air conditioning is very large when it is used. In fact, these problems are usually relatively easy to solve, mainly because of the service attitude of workers.

Solution:

(1) The outdoor unit is not installed correctly. First make clear the wall structure, such as precast concrete, and the indoor side is mostly office space or bedroom and study. It is relatively empty, and there will be revolving surround sound indoors, which belongs to the architectural structure and the interior decoration effect of the house. This phenomenon belongs to objective factors.

(2) The stress on the screws at the bottom of the outdoor unit is uneven, and the fastening screws at the bottom plate are loose. When the compressor is running, the vibration will drive the chassis to jump and produce noise. Tighten the anchor screw with a wrench and tighten it evenly at the same time. It is forbidden to fasten one of the screws in place first, which will cause uneven fixing force.

(3) The outdoor unit bracket is not installed horizontally, or the fixing screw of the combined bracket is not properly tightened and deformed, which will cause the outdoor unit foot to be uneven. At this time, the outdoor unit bracket should be rearranged, adjusted horizontally or fastened with the fixing screws of the bracket.

2, compressor quality problems

Compressor is the heart of central air conditioning. The quality of compressor directly determines the noise level of central air conditioning, and the quality of compressor directly controls the use effect of central air conditioning. Many low-end central air conditioners use relatively cheap compressors to control costs, and such central air conditioners may be noisy when used.

Solution:

The compressor (1) has poor performance and produces low-frequency vibration and hum when working, so the compressor can be adjusted and replaced.

(2) The outdoor unit is too dirty, or there are foreign objects in the cabinet, which generate noise by rubbing with the fan; Just clean up the foreign body.

(3) Spare parts, usually the compressor cylinder is stuck or the compressor starting capacitor is damaged, and the damaged spare parts can be replaced.

3, the wall thickness is not enough

In addition to the quality and installation process of the central air conditioner itself, the wall thickness of the external machine is also a very important factor in the noise intensity. The walls of some old houses are thin or hollow. When the air conditioner is started, it will produce vibration and low-frequency noise. The greater the power of central air conditioning, the greater the relative noise. Therefore, when installing central air conditioning, please install workers to choose thick walls as much as possible to avoid greater noise.

Solution:

When the fan is running, it rubs against the outer wall, so it is necessary to adjust the distance between the fan and the outer wall in time. In addition, it is also possible that the fan is stuck. Add some lubricating oil to the air conditioning fan shaft to ensure the smooth rotation of the fan.