Transmission failure is a problem that plagues many car owners. Identifying and resolving transmission failures requires specialized skills and knowledge. PHP editor Xinyi brings detailed gearbox fault diagnosis and repair guide to solve your problems. This guide will introduce the common symptoms, diagnosis methods and repair strategies of transmission failure one by one, so that you can fully understand the response to transmission failure.
1. The gearbox temperature is too high
During driving, the computer displays an alarm: the gearbox temperature is too high; or after driving for a while, you feel that the gearbox is overheated, or even hot to your hands. This should be caused by the gearbox being frequently overloaded and unable to effectively control the temperature.
2. The car slips or has an impact
If the car does not move when the D or R gear is engaged, or the car reacts very slowly after impact, or the engine speed is very high but the vehicle speed is very slow, it means that the mechanism inside the gearbox There is a problem with the transmission part.
3. Odor occurs in the gearbox body
The gearbox body relies on hydraulic oil to work. When the oil temperature is too high, some combustion will occur, and these odors will come out, which means that certain operations in the gearbox body Part is not working properly.
4. Difficulty in shifting gears and a sense of frustration
During starting or driving, shifting, shifting, and shifting are awkward and laborious, as if something has been stuck. There is a feeling of jerking, vibration, and frustration. Sometimes the car is easy to hang when the car is cold. It is difficult to put the car into gear when the car is hot, which brings a lot of discomfort; the reason is that the relevant gears and other components in the gearbox cannot be sufficiently lubricated, and a lasting lubricating film cannot be formed, making the components unable to work smoothly.
5. Automatic transmission and impact feeling
There is no power at the start. The car has obvious jerking and frustration when driving at low or medium speeds. At the same time, the tachometer needle on the instrument panel floats up and down; the accelerator is pressed sharply while driving at medium or high speeds. When the pedal is pressed, the car slips, the tachometer needle rises rapidly and there is an obvious impact; when shifting from P to R and D, the car has an obvious impact and shifts.
1. PLC fault types.
1. External device failure.
External devices refer to various switches, sensors, actuators, loads, etc. that are directly connected to the PLC working process. Failure of these devices will directly affect the control function of the PLC system. Therefore, when repairing PLC, you must first distinguish whether it is an external device failure or a failure of the PLC itself.
2. System failure.
1) System fault is a global fault that affects the operation of the PLC system.
2) PLC system faults can be divided into fixed faults and accidental faults.
3) After a failure occurs, the system can be restarted to return to normal, which is an accidental failure. If the system cannot be restored after restarting, but the hardware or software needs to be replaced before the system can return to normal, it is considered a fixed fault.
3. Hardware failure.
PLC hardware fault mainly refers to faults caused by damage to the templates and circuits in the PLC system.
4, software failure.
PLC software faults include software errors, operating errors, etc. PLC software faults can generally be viewed and checked through the PLC's own self-diagnostic test function or software.
Second, the failure rate of PLC control system.
1) CPU and memory failure rate accounts for 5%.
2) The I/O module failure rate accounts for 15%.
3) Sensor and switch failure rate accounts for 45%.
4) The actuator failure rate accounts for 30%.
5) The failure rate in wiring and other aspects accounts for 5%.
Three, key areas where PLC failures occur frequently.
1) Relays and contactors.
2) Valves and gates.
3) Switches, extreme positions, safety protection, and some components or equipment for on-site operation.
4) Sub-equipment in PLC system.
5) Sensors and instruments.
6) Noise from power supply, ground wire, and signal wire.
Fourth, the basic sequence of repairing PLC.
1. Use your mouth first and then your hands.
1) When repairing PLC, do not do it directly immediately, but first ask about the situation before and after the fault occurred and the fault phenomenon;
2) If you are repairing an unfamiliar PLC, you should first understand its working principle.
2. Clean first and then repair.
When repairing the PLC, you can open the machine and clean the PLC first.
3. PLC inspection is done from the outside first and then inside.
When repairing the PLC, first check the external phenomena and causes. If the outside is normal, then check the inside of the PLC.
4. Determine if there is no power first and then judge if it is powered on.
First of all, when there is no power, first determine whether the fuse is damaged and whether there is no power to determine the fault point. If it cannot be determined, power on and check the PLC again.
5. Basic process of PLC system maintenance and troubleshooting.
Overall diagnosis: You can find out the general direction of the fault point according to the overall inspection flow chart, and then gradually refine it to find out the specific fault.
1. Power supply fault diagnosis.
If the power light does not light up, you need to check the power supply system and the power light itself.
2. Run fault diagnosis.
If the power supply is normal and the operation indicator light does not light up, it means that the system may terminate normal operation due to some abnormal reasons.
3. Input and output fault diagnosis.
1) Input and output are the channels for information exchange between PLC and external equipment;
2) Whether input and output is working properly is not only related to the input/output unit, but also related to the connection wiring, terminal blocks, fuses and other components Status related.
Sixth, basic steps to find general PLC faults.
When PLC is being repaired, plug in the programmer, turn the switch to the RUN position, and then search according to the following steps:
1) If the PLC stops at some position or state (place) where the output is activated, it is usually in the middle status, then search for the signal that causes the next operation to occur, and the programmer will display the ON/OFF status of the signal;
2) If a signal is input, compare the status displayed by the programmer with the LED indication of the input module. If the results are inconsistent, This indicates that the input module needs to be replaced. Before replacing the module, you need to check whether the I/O expansion cable and related connections are normal;
3) If the input status is consistent with the LED indication of the input module, compare the status of the LED and the input device. If they are different, you need to measure the input module. If problems are found, I/O devices, field wiring, power supplies, etc. need to be replaced. Otherwise, the input module needs to be replaced;
4) If the signal is a coil and there is no output or the output is in a different state from the coil, you need to use a programmer to check the output driving logic and check the program list;
5) If the signal is timing and stops at a non-zero value less than 999.9, the CPU module needs to be replaced;
6) If this signal controls a counter, you need to check the logic that controls the reset first, and then check the counter signal. Then check and determine whether the relevant components are abnormal and need to be replaced. 3. Air conditioning fault diagnosis and repair?
Maintenance method:
The fault characteristics of the air conditioner circuit board power circuit are usually that the fuse is intact and the fuse burns as soon as the machine is turned on. For the former fault, you can use the AC setting of the multimeter to measure whether the primary and secondary voltages of the transformer are 220V and 10-13V. If so, use the DC setting of the multimeter to measure whether the 7812 and 7805 have +9-12V and +5V voltages, so that they can be distinguished. Faulty part. For the latter, it means that there is a short circuit in the circuit. Use the ohm block of a multimeter to detect the resistance to determine the short circuit part of the circuit. At the same time, the segmentation method can also be used to check. For example, you can disconnect the primary winding of the transformer and power on the test machine. If the fuse is still burned, it means that the burned fuse is due to a short circuit in the varistor or ceramic capacitor. Otherwise, it is due to a short circuit in the transformer. Or the rectifier tube has a short circuit.
4. How to diagnose and quickly repair the mainboard failure of the balancing car?
1. Unable to shut down
①The contact is too long, long press to shut down.
②The switch is broken.
③The assistant class is broken.
④The motherboard is broken.
2. Alarm when powering on
① Motor failure, need to replace the motor with a new one.
②The operating current is too large, it’s time to replace the motherboard with a new one.
③The contact plate is broken, replace it with a new one.
④The balance car beeped and the car shook. Most problems can be restored to normal by adjusting the system of the balancing car.
5. How to diagnose and repair common air conditioner faults?
It makes a harsh noise after turning on the phone. After shutdown, the indoor fan rotates slowly.
Analysis: Based on the phenomenon analysis, it is initially determined that the indoor motor power supply is faulty. Check the supply voltage to the indoor fan. The motor has 100V voltage in the stopped state. After shutdown, the indoor motor still runs slowly and continuously. The heating of the indoor motor causes the plastic motor frame to deform when heated, causing the position of the plastic sealed motor to shift. This will cause the crossflow fan to collide with the chassis and make an unpleasant noise, as well as a burning smell. It is determined that the thyristor controlled by the fan is damaged.
Solution: Replace the main control device
The fan does not start running, and the indoor fan does not stop and shut down.
Analysis: According to the fault phenomenon, it was found that the indoor fan was powered on when it was running. The indoor fan is still running after being turned on remotely. It was initially determined that there was a power supply failure to the indoor motor. Check the supply voltage to the indoor fan. In the power-on or power-off state, the motor has a 158v voltage output. Therefore, if the indoor motor runs after being powered on, it is determined that the thyristor of the fan control is damaged.
Solution: After replacing the controller with the same type, test whether the operation is normal.
6. How to judge computer hardware faults and repair methods
1. How to judge computer hardware failure
2. Common computer hardware failures and repair methods
For the above faults, you can try some simple repair methods first, such as cleaning dust, updating drivers, etc. If the problem still cannot be solved, the corresponding hardware components need to be replaced. When replacing hardware, you need to pay attention to choosing products that are compatible with the original hardware and follow the correct steps.
In short, discovering and solving computer hardware faults in time can effectively extend the service life of the computer and improve work efficiency. I hope that through this article, you can better understand the diagnosis and repair methods of computer hardware faults. Thank you for reading!
Take common ASUS and Lenovo brands and computers with win 10 operating system as an example. The method to check whether the computer sound card is damaged is as follows:
1. Whether the driver output is "mute" by default. Click the small sound icon (small speaker) in the lower right corner of the screen, a volume adjustment slider will appear, and there is a "Mute" option below. Click the check box in front of it, clear the check mark in the box, and you can pronounce normally.
2. The sound card driver is faulty. After confirming that the computer is normal, go to "Device Manager" and check whether the sound card driver is normal and whether there is an "exclamation mark" under the "Sound, Video and Game Controllers" option. If so, just reinstall the sound card driver.
Computers are an indispensable tool in our daily work and life, but hardware failures occasionally occur. Knowing how to accurately diagnose computer hardware failures allows us to better solve problems and improve work efficiency. This article will introduce the criteria for determining computer hardware faults to help readers correctly diagnose faults and take appropriate solutions.
Before judging computer hardware failure, we first need to understand some common signs of hardware failure:
Blue screen and freeze: Frequent blue screen or freeze on the computer may be a symptom of hardware failure. Strange noises: Strange noises coming from your computer may be a sign of hardware failure. Device is unresponsive: The mouse, keyboard, or other external device is not working properly. There may be a problem with the hardware device itself. Decreased performance: Your computer runs slower and applications become unresponsive, possibly due to hardware issues. Abnormal temperature: The computer has abnormally high temperature or overheating, which may be the cause of hardware failure.When we encounter the above signs, in order to accurately determine whether it is a hardware failure, we can take the following methods:
Make sure that all hardware devices are connected properly, including power cords and data cables, memory sticks, etc. Sometimes, poor device connections can lead to hardware failure.
Use professional hardware detection tools, such as hardware monitors, diagnostic software, etc., to conduct a comprehensive detection of the hardware to determine whether there is a fault.
When the computer fails, there will be some error codes or warning messages. Observing these codes and information can help us determine the cause of the failure and possible hardware failure.
Identify faulty equipment by troubleshooting hardware equipment one by one. For example, after disconnecting a certain hardware device, run the computer again to see if the problem still occurs.
Once it is determined that the computer has a hardware failure, we can take the following methods to solve the problem:
If it is determined that a hardware device is faulty, it must be replaced in time� �For example, replace a new memory module, hard drive or power supply.
For some more expensive hardware, we can consider repair or refurbishment to solve the fault. For example, find a professional technician to repair the motherboard or graphics card.
If you cannot solve the problem yourself, you can seek professional hardware repair services and let professionals repair your computer.
In short, there are many criteria for judging computer hardware failure, but we need to analyze and judge based on the specific situation. I hope this article can help you better understand and diagnose computer hardware failures and choose the correct solution. Thanks for reading!
1. Car air conditioner does not cool at all. Loss of cooling function is the most common phenomenon in the air conditioning system. The main reasons for this failure are as follows.
(1) No refrigerant liquid in the refrigeration system
When there is a refrigerant leakage in the system, this will happen if it is not discovered for a long time. In response to this situation, we must first identify the leaking point and repair it, then re-evacuate and fill the refrigerant liquid.
(2) Refrigeration system failure
Internal blockage of the pipeline is the most common failure of the refrigeration system. When the compressor is working, if a certain part of the refrigeration system is seriously blocked and there is no circulation of refrigerant liquid, the refrigeration effect will be lost. At this time, if a pressure gauge is used to detect the pressure values on the high and low pressure sides of the refrigeration system, it can be found that the pressure value on the high pressure side is lower than normal, while the pressure value on the low pressure side is in a vacuum state, and there is an obvious temperature difference between the front and rear of the blocked part. The fault usually occurs in the reservoir dryer or expansion valve. Therefore, nitrogen can be blown against the inlet or outlet of the liquid storage dryer or expansion valve. If it is not smooth, it means it is clogged and needs to be replaced.
(3) The compressor is faulty
The compressor is stuck or internally damaged, the compressor cylinder and compressor pad have blow-by air, the intake and exhaust valves are damaged, the compressor electromagnetic clutch coil is short-circuited, etc., which can cause the compressor to be unable to compress and refrigeration. fluid or poor compression. At this time, if you use a pressure gauge to detect the intake pressure and exhaust pressure when the compressor is working, you can find that the two pressures are the same or have little difference. When the engine speed is increased, the pressure value still does not change significantly; touch the compressor with your hand. There is not much temperature difference between the intake pipe and the exhaust pipe. When the compressor has a blow-by fault between the cylinder and the compressor pad, the compressor will feel very hot when you touch it with your hands. When this kind of failure occurs, it usually needs to be replaced.
2. The car air conditioner is not cold enough. The reasons why the output cooling capacity is insufficient (that is, the air conditioner blown out is not cool) are as follows.
(1) Insufficient refrigerant fluid
For most cars, the decrease in cooling capacity is caused by insufficient refrigerant fluid. The cause of insufficient refrigerant is mostly due to trace leaks in the system. The phenomenon of insufficient refrigerant can also be observed from the sight glass above the drying tank. When the air conditioner is operating normally, if there are continuous and slow bubbles in the sight glass, it means there is insufficient refrigerant. If there is obvious bubble flipping, the refrigerant liquid is seriously insufficient. If the refrigerant liquid is insufficient, add refrigerant liquid. However, please note that if you add it from a low-pressure place, do not invert the refrigerant liquid to prevent "liquid shock" in the compressor due to liquid refrigerant liquid on the low-pressure side and damage to the compressor. ; If the refrigerant is added from the high-pressure side, it is forbidden to start the engine to prevent the refrigerant from flowing back into the bottle.
(2) Excessive addition of refrigerant liquid
For air conditioning systems that have just been repaired, the cause of insufficient cooling is often due to the addition of too much refrigerant liquid. There are certain requirements for the proportion of the volume of refrigerant liquid in each component in the air conditioning system. If the proportion is too large, it will affect its heat dissipation effect. This is because the refrigerant liquid in the refrigeration system is closely related to the heat dissipation capacity of the high-pressure side. A strong heat dissipation capacity requires more refrigerant liquid; a weak heat dissipation capacity requires less refrigerant liquid. Whether the refrigerant liquid is injected too much can be observed from the sight glass above the dry noise tank. For example, when the car air conditioner is running, no bubbles can be seen in the sight glass, and there are no bubbles after the compressor stops, it must be refrigeration. Too much fluid. If there is indeed too much refrigerant, you can slowly release some from the maintenance port on the low-pressure side of the air conditioning system.
(3) There is air in the air-conditioning system
Once air enters the air-conditioning system, or the vacuum is not completely evacuated during maintenance, or air infiltrates when filling the refrigerant liquid, it will cause insufficient cooling capacity. This is because air is a poor heat conductor. It cannot dissolve in the refrigerant liquid under the pressure and temperature of the refrigeration system. Therefore, the air must occupy a certain space of the refrigerant liquid, affecting its heat dissipation ability. This air will also travel with the refrigerant liquid in the air conditioning system. During the cycle, the refrigerant volume ejected from the expansion valve decreases, resulting in a decrease in the cooling capacity of the air conditioner. Too much air in the refrigerant liquid can be observed from the inspection hole above the drying tank. When the air conditioner is operating normally, if there is continuous and rapid flow of bubbles in the inspection hole, it means there is too much air in the system. At this time, it is necessary to vacuum the refrigeration system and then refill it with new refrigerant liquid.
(4) Refrigerant liquid and refrigeration oil contain too many impurities
Excessive impurities in refrigerant liquid and refrigeration oil will cause partial blockage in the system and cause insufficient cooling capacity.
The simple inspection method is: in the refrigeration pipes and components, if there is a very obvious sudden change of heat and cold in the adjacent place, it means that the place is blocked. Therefore, when repairing air conditioners, it is very important to choose qualified refrigerant fluid, especially do not choose those "three noes" products.
(5) There is moisture seeping into the air conditioner refrigerant
There is a component in the refrigeration system which is the drying tank (bottle). Its main task is to absorb the water in the refrigerant liquid to prevent the cooling capacity from decreasing due to excessive water in the refrigerant liquid. But when the desiccant in the drying tank is in a hygroscopic saturated state, the water can no longer be filtered out. When the refrigerant liquid passes through the expansion valve orifice, due to the rapid drop in pressure and temperature, the water in the coolant will Freezing occurs in the small holes, resulting in poor circulation of the refrigerant, increased resistance, or complete inability to flow. Whether there is water in the system can be determined by shutting down the system for a while and checking whether the system returns to normal. If so, it can be determined. For any failure involving excessive water content in the refrigerant liquid, the desiccant or drying tank should be replaced. At the same time, the system should be evacuated again and a new appropriate amount of refrigerant liquid should be re-injected.
(6) The compressor drive belt is too loose
If the air conditioning compressor drive belt is loose, the compressor will slip during operation, causing the transmission efficiency to decrease, the compressor speed to decrease, and the delivery volume of compressed refrigerant to decrease, thus directly causing the The cooling capacity of the air conditioning system is reduced. The drive belt inspection method is when the engine is stopped. Turn the belt by hand in the middle position of the drive belt. It is better if it can turn 90°. If the rotation angle is too much, the drive belt is loose. The diagnosis and troubleshooting of automobile air conditioner faults should be tightened. If it cannot be turned by hand, If it moves, the drive belt is too tight and should be loosened slightly. If the tightening is ineffective or the drive belt has cracks, aging or other damage, replace it with a new one.
(7) The heat dissipation capacity of the condenser is reduced
Due to the different working environment of the car, the surface of the condenser installed in front of the car engine will be covered with oil, dirt or debris, thus reducing its heat dissipation capacity. In addition, cooling fan failure, such as loose drive belt, reduced fan speed or high fan speed, will lead to a decrease in the heat dissipation capacity of the condenser. At this time, a soft brush should be used to remove dirt on the surface of the condenser. Failure of the electric fan should also be Eliminate it promptly. In addition, the air conditioner's cooling capacity may be insufficient due to wear of the compressor or lax valve closure.
3. Sometimes there is no fault during air-conditioning
The reason for the intermittent and uneven air-conditioning output is usually a fault in the electrical part, such as circuit switch, fan switch, fan motor failure, or compressor coil and solenoid valve open circuit, poor grounding or Loose connection;
It may also be caused by loose compressor connection device and blocked evaporator.
You can use a multimeter to check whether the circuit switch, fan switch, and fan motor are normal; check the tightness of the compressor belt and whether the electromagnetic clutch coil is in good condition.
1. Car air conditioner does not cool at all. Loss of cooling function is the most common phenomenon in the air conditioning system. The main reasons for this failure are as follows.
(1) There is no refrigerant liquid in the refrigeration system
When there is a refrigerant liquid leakage in the system and it is not discovered for a long time, this will result. In response to this situation, we must first identify the leaking point and repair it, then re-evacuate and fill the refrigerant liquid.
(2) Refrigeration system failure
Internal blockage of the pipeline is the most common failure of the refrigeration system. When the compressor is working, if a certain part of the refrigeration system is seriously blocked and there is no circulation of refrigerant liquid, the refrigeration effect will be lost. At this time, if a pressure gauge is used to detect the pressure values on the high and low pressure sides of the refrigeration system, it can be found that the pressure value on the high pressure side is lower than normal, while the pressure value on the low pressure side is in a vacuum state, and there is an obvious temperature difference between the front and rear of the blocked part. The fault usually occurs in the reservoir dryer or expansion valve. Therefore, nitrogen can be blown against the inlet or outlet of the liquid storage dryer or expansion valve. If it is not smooth, it means it is clogged and needs to be replaced.
(3) The compressor is faulty
The compressor is stuck or internally damaged, the compressor cylinder and compressor pad have blow-by air, the intake and exhaust valves are damaged, the compressor electromagnetic clutch coil is short-circuited, etc., which can cause the compressor to be unable to compress and cool. fluid or poor compression. At this time, if you use a pressure gauge to detect the intake pressure and exhaust pressure when the compressor is working, you can find that the two pressures are the same or have little difference. When the engine speed is increased, the pressure value still does not change significantly; touch the compressor with your hand. There is not much temperature difference between the intake pipe and the exhaust pipe. When the compressor has a blow-by fault between the cylinder and the compressor pad, the compressor will feel very hot when you touch it with your hands. When this kind of failure occurs, it usually needs to be replaced.
2. The car air conditioner is not cold enough. The reasons why the output cooling capacity is insufficient (that is, the air conditioner blown out is not cool) are as follows.
(1) Insufficient refrigerant fluid
For most cars, the decrease in cooling capacity is caused by insufficient refrigerant fluid. The cause of insufficient refrigerant is mostly due to trace leaks in the system. The phenomenon of insufficient refrigerant can also be observed from the sight glass above the drying tank. When the air conditioner is operating normally, if there are continuous and slow bubbles in the sight glass, it means there is insufficient refrigerant. If there is obvious bubble flipping, the refrigerant liquid is seriously insufficient. If the refrigerant liquid is insufficient, add refrigerant liquid. However, please note that if you add it from a low-pressure place, do not invert the refrigerant liquid to prevent "liquid shock" in the compressor due to liquid refrigerant liquid on the low-pressure side and damage to the compressor. ; If it is added from the high-pressure side, it is forbidden to start the engine to prevent the refrigerant liquid from flowing back into the bottle.
(2) Excessive addition of refrigerant liquid
For air conditioning systems that have just been repaired, the cause of insufficient cooling is often due to the addition of too much refrigerant liquid. There are certain requirements for the proportion of the volume of refrigerant liquid in each component in the air conditioning system. If the proportion is too large, it will affect its heat dissipation effect. This is because the refrigerant liquid in the refrigeration system is closely related to the heat dissipation capacity of the high-pressure side. A strong heat dissipation capacity requires more refrigerant liquid; a weak heat dissipation capacity requires less refrigerant liquid. Whether the refrigerant liquid is injected too much can be observed from the sight glass above the dry noise tank. For example, when the car air conditioner is running, no bubbles can be seen in the sight glass, and there are no bubbles after the compressor stops, it must be refrigeration. Too much fluid. If there is indeed too much refrigerant, you can slowly release some from the maintenance port on the low-pressure side of the air conditioning system.
(3) There is air in the air-conditioning system
Once air enters the air-conditioning system, or the vacuum is not completely evacuated during maintenance, or air infiltrates when filling the refrigerant liquid, it will cause insufficient cooling capacity. This is because air is a poor heat conductor. It cannot dissolve in the refrigerant liquid under the pressure and temperature of the refrigeration system. Therefore, the air must occupy a certain space of the refrigerant liquid, affecting its heat dissipation ability. This air will also travel with the refrigerant liquid in the air conditioning system. During the cooling period, circulation occurs, resulting in a decrease in the amount of refrigerant liquid ejected from the expansion valve, resulting in a decrease in the cooling capacity of the air conditioner. Too much air in the refrigerant liquid can be observed from the inspection hole above the drying tank. When the air conditioner is operating normally, if there is continuous and rapid flow of bubbles in the inspection hole, it means there is too much air in the system. At this time, it is necessary to vacuum the refrigeration system and then refill it with new refrigerant liquid.
(4) Excessive impurities in the refrigerant liquid and refrigeration oil
Excessive impurities in the refrigerant liquid and refrigeration oil will cause partial blockage in the system and cause insufficient cooling capacity.
The simple inspection method is: in the refrigeration pipes and components, if there is a very obvious sudden change of heat and cold in the adjacent place, it means that the place is blocked. Therefore, when repairing air conditioners, it is very important to choose qualified refrigerant fluid, especially do not choose those "three noes" products.
(5) Water penetrates into the air-conditioning refrigerant liquid
There is a component in the refrigeration system which is the drying tank (bottle). Its main task is to absorb the water in the refrigerant liquid to prevent it from being damaged by the water in the refrigerant liquid. Excessive cooling capacity drops. But when the desiccant in the drying tank is in a hygroscopic saturated state, the water can no longer be filtered out. When the refrigerant liquid passes through the expansion valve orifice, due to the rapid drop in pressure and temperature, the water in the coolant will Freezing occurs in the small holes, resulting in poor circulation of the refrigerant, increased resistance, or complete inability to flow. Whether there is water in the system can be determined by shutting down the system for a while and checking whether the system returns to normal. If so, it can be determined. For any failure involving excessive water content in the refrigerant liquid, the desiccant or drying tank should be replaced. At the same time, the system should be evacuated again and a new appropriate amount of refrigerant liquid should be re-injected.
(6) The compressor drive belt is too loose
If the air conditioning compressor drive belt is loose, the compressor will slip during operation, causing the transmission efficiency to decrease, the compressor speed to decrease, and the delivery volume of compressed refrigerant to decrease, thus directly causing the The cooling capacity of the air conditioning system is reduced. The drive belt inspection method is when the engine is stopped. Turn the belt by hand in the middle position of the drive belt. It is better if it can turn 90°. If the rotation angle is too much, the drive belt is loose. The diagnosis and troubleshooting of automobile air conditioner faults should be tightened. If it cannot be turned by hand, If it moves, the drive belt is too tight and should be loosened slightly. If the tightening is ineffective or the drive belt has cracks, aging or other damage, replace it with a new one.
(7) The heat dissipation capacity of the condenser is reduced
Due to the different working environment of the car, the surface of the condenser installed in front of the car engine will be covered with oil, dirt or debris, thus reducing its heat dissipation capacity. In addition, cooling fan failure, such as loose drive belt, reduced fan speed or high fan speed, will lead to a decrease in the heat dissipation capacity of the condenser. At this time, a soft brush should be used to remove dirt on the surface of the condenser. Failure of the electric fan should also be Eliminate it promptly. In addition, the air conditioner's cooling capacity may be insufficient due to wear of the compressor or lax valve closure.
3. Sometimes there is no fault during air-conditioning
The reason for the intermittent and uneven air-conditioning output is usually a fault in the electrical part, such as circuit switch, fan switch, fan motor failure, or compressor coil and solenoid valve open circuit, poor grounding or Loose connection;
It may also be caused by loose compressor connection device and blocked evaporator.
You can use a multimeter to check whether the circuit switch, fan switch, and fan motor are normal; check the tightness of the compressor belt and whether the electromagnetic clutch coil is in good condition.
4. The compressor cannot stop automatically normally
Common reasons why the compressor cannot stop automatically include damaged low-voltage (or low-temperature) protection switch, broken high-pressure pressure switch, malfunctioning thermostat, short circuit of wires, etc.
When encountering this phenomenon, first check the suction pressure and exhaust pressure of the compressor air inlet. If the suction pressure is lower than the jump-off value, it means that the low-pressure switch is damaged;
If the exhaust pressure is higher than the jump-off value, it means that the low-pressure switch is damaged. The high voltage switch is damaged;
If damage is found, the pressure relay can be replaced directly. Then check the thermostat, cut off the power supply to the thermostat, and see if the thermostat can start up normally. If not, replace it. Finally, check whether the circuit is short-circuited and whether the circuit is damaged.
5. There is noise when the air conditioning system is running
Insufficient compressor refrigeration oil causes dry friction or internal wear of the compressor;
Excessive or insufficient refrigerant fluid;
Excessive refrigeration oil;
Loose or worn transmission belts, cooling The motor fan touches other parts;
The blower motor has mechanical friction;
The motor bearings are oil-free.
If the air conditioner makes an abnormal noise during operation, you should immediately determine where it is coming from, and then stop the machine for inspection.
First check whether the compressor transmission belt is too loose or worn, and adjust or replace it if necessary;
After trial operation, if it is found that the blades of the fan motor rub against other parts, adjust or correct them;
Finally check whether the motor bearings are missing Oil, if possible, it can be disassembled and lubricating oil (grease) added, otherwise the compressor should be replaced.
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