Based on the theoretical knowledge of automobile air conditioning,
Combine the theory with automobile air conditioning and refrigeration
This paper analyzes the existing defects, expounds the maintenance methods, and analyzes a Santana car with fault diagnosis diagram.
2000
The example analysis, diagnosis and maintenance were carried out for the lack of refrigeration, and finally the fault was successfully eliminated.
Cheng.
Detection, diagnosis and maintenance of insufficient refrigeration
1
order
Insufficient refrigeration of air condition is a common fault of air conditioning system,
This is manifested in the air conditioning system.
After running for a long time, although the temperature in the carriage can drop, the wind blown out of the air outlet is not cold, no.
Cool and comfortable feeling. Under normal circumstances, when the outdoor temperature is
34
When the temperature is around 100℃, the wind will come out.
The oral temperature is
0~5
℃, at this time, the temperature inside the car should reach
20~25
If this temperature is not reached.
Degree, that is, there is something wrong with the air conditioning system.
2
Santana automobile
2000
Fault diagnosis of insufficient refrigeration in air conditioning system
2. 1
Fault phenomenon
A Santana
2000
The air conditioner works well when the car starts in the morning, but when the car works.
About two hours later,
It is found that the air conditioning refrigeration effect is not good,
Especially when driving out at noon,
The temperature inside the car will never drop.
2.2
Santana automobile
2000
Fault analysis of insufficient refrigeration in air conditioning system
Through the fault phenomenon,
It can be judged that it is caused by poor refrigeration of the air conditioning system.
According to this process
It can be determined from the picture that it is not that the air conditioner in the car does not work.
(
That is, the blower works well.
,
The compressor is also working normally.
often
)
. Therefore, connect the air conditioning pressure gauge for testing. Check automobile air conditioning refrigeration with pressure gauge
three
System failures are generally divided into two states: compressor shutdown and operation.
(After the compressor stops running.
10h
After the above operation, if the high-low table shows that the high-pressure side and the low-pressure side of the compressor should be the same value.
The displayed values are not equal, which indicates that there is blockage inside the system, and the expansion valve, liquid storage cylinder and pipeline need to be treated.
Part of the inspection. When the compressor is running, control the engine speed at
1500
~
In 2000
/
department
, start the air conditioner to make the compressor work, under normal circumstances, the low side pressure.
The force is about
150
~
250 kPa
The high pressure side pressure is about
1400
~
1600 kpa
)
So through the early stage.
Warm up, let the car reach the normal working temperature, turn on the car air conditioner, and then test it manually.
air outlet
(
automobile
)
The temperature is not very cold. And measured with a thermometer. At this time,
The measured actual temperature is
22.3
℃。
Observe the value of air conditioning pressure gauge.
At this time, the low pressure of the car
It is obviously higher than the normal value, while the pointer of the high pressure meter is slightly higher than the normal value.
2.3
Santana automobile
2000
Fault diagnosis of insufficient refrigeration in air conditioning system
According to the indication of the pressure gauge does not meet the normal value, the following fault diagnosis can be carried out.
Rest.
(
1
) high and low pressure gauge indicates that it is lower than normal at the same time. This may be due to the refrigerant.
Insufficient, it can be found that the high-pressure pipe is slightly hot and the low-pressure pipe is slightly cold, but the temperature difference is not big.
You can see from the mirror that every other one
1
~
2s
There is foam. At this point, first check whether there is any leakage.
Point, fill the leak, and then add refrigerant.
(
2
) The low pressure gauge is much lower than the normal value. At this time, you can see the fuzzy fog flow in the mirror, high and low,
There is no temperature difference in the low-pressure pipe, and the cold air is not cold, indicating that the refrigerant leakage is serious.
(
three
) The indication of low pressure gauge is close to zero, and that of high pressure gauge is lower than normal. At this time, the air conditioner
The system often shows that the outlet air is not cold, and the pipeline before and after the expansion valve is frosted. Cause, one side
The expansion valve may be blocked by frost, which prevents the refrigerant from circulating in the system. At this time, it should be
four
Repeatedly vacuumizing and re-adding refrigerant; On the other hand, it may be the temperature loss of expansion valve.
Bad, resulting in the expansion valve is not open, at this time should check the temperature sensor.
(
four
) High and low pressure gauges indicate too low. This may be an internal fault of the compressor, such as
The valve plate gasket and valve plate are damaged, so the compressor needs to be replaced.
(
five
) High and low pressure gauges are higher than normal. The surface temperature ratio of compressor suction pipe is normal.
When the situation is low, it is wet and cold (commonly known as sweating)
. Because the expansion valve is too wide,
Refrigerant in evaporator "exceeds demand"
, affecting evaporation, the corresponding heat absorption is reduced, resulting in
The air conditioner is not cold enough. At this time, if the opening of the expansion valve can be adjusted, the opening should be reduced; such as
If not adjustable, replace the expansion valve.
(
six
) The pressure on both sides of high and low pressure is too high. This shows that there is too much refrigerant and the hands are separated.
Don't touch the intake pipe and exhaust pipe of the compressor. The high-pressure side feels hot, and the low-pressure side can see it.
When it comes to frost, the compressor of the air conditioning system turns off the power supply and stops running, and the rest continue to work.
When,
exceed
45s
In the future,
There is still no bubble flow in the oscilloscope,
It can be concluded that refrigeration
If there is too much refrigerant, the excess refrigerant should be discharged.
(
seven
) The indication of low pressure gauge is too high, and that of high pressure gauge is slightly higher. This may be condenser cooling.
Insufficient, if the condenser is cooled with cold water and the pressure of the pressure gauge becomes normal, it can be
The conclusion is that the condenser is insufficiently cooled. If there is such a fault, the air conditioner will be cold when it is first turned on.
Good effect, long working time and poor refrigeration effect. If the fins of the condenser are blocked,
If the engine water temperature is too high and the air volume of the condenser is not enough, it may be the fan or wind of the condenser.
There is something wrong with the fan belt.
(
eight
) The low pressure gauge indicates zero or negative pressure, and the high pressure gauge indicates normal or high pressure. Cold wind time
However, it is not cool, and sometimes it is normal. This phenomenon shows that there is water or desiccant in the refrigeration system to absorb water.
five
When the capacity reaches saturation, water enters the refrigeration cycle system and freezes and dissolves at the small hole of the expansion valve.
After the chemistry returns to normal, the drying bottle should be replaced or vacuumized repeatedly to eliminate the system.
It's damp inside.
(
nine
) low pressure gauge indicates low pressure gauge indicates high pressure gauge. This phenomenon is generally a refrigeration system.
System blockage, which often occurs in the position where there are small channels in the cross section of the refrigeration system, is easy to block.
Most parts of the plug are on the high pressure side of the refrigeration system, such as drying filter and expansion.
Valve filter screen, etc. And the blocking phenomenon is usually contaminated by moisture and dust contained in the refrigerant.
Things and shelter parts often frost. When the blockage is found, clear it.
Parts are removed or replaced, and the refrigeration system is seriously blocked, so it should be completely removed and divided.
Sectional cleaning.
(
10
) Low gauge pressure is too high and high gauge pressure is too low. This phenomenon usually indicates stress.
There is leakage inside the compressor, so the compressor should be replaced or repaired.
(
1 1
) The low pressure gauge is slightly higher and the high pressure gauge is slightly lower. Without cold air, the compressor suction pipe condenses.
There is moisture or frost, which may be that the expansion valve is damaged, so it needs to be replaced and charged.
Coolant.
According to the above judgment, it is caused by poor heat dissipation of the condenser, so this car is
Drive to the garage and spray the condenser radiator with cold water directly, and then reconnect the air conditioning pressure.
Force table, observing the numerical value, found that after more than ten minutes, the low pressure and high pressure of the refrigeration system were
After returning to normal. After driving the car back to the workshop from the car wash room, it was found through observation that
The condenser fins of automobiles are full of dust,
After cleaning the condenser.
begin
Engine, turn on the air conditioner, and then measure the system pressure of this car. According to the measurement,
The values displayed by the high and low pressure meters are all within the working range, and the refrigeration effect is also very good.
six
All right.
Next, put the car in direct sunlight for testing.
Turn on the air conditioner.
After about two hours, measure the high and low pressure values again, which are still within the normal range, and
The refrigeration effect is also satisfactory. So far, the fault of the refrigeration system has been successfully eliminated.
three
abstract
Insufficient refrigeration of air conditioner is a common problem of automobile air conditioner.
,
Automobile air conditioning maintenance personnel
It is necessary to understand the theoretical knowledge of air conditioning and the working principle of each system. This article is about Santana.
2000
Analyze the lack of refrigeration, and cooperate with certain procedures to determine that the fault is certain.
Steps, there is a clear idea to solve the problem, for the future encounter with insufficient refrigeration.
Fault is also a prescription for summing up. If you encounter any fault, you will also check the information to sum up your experience and have a clear idea.
Think about solving all kinds of intractable diseases.
refer to
[ 1]
Xia Yunhua
.
automobile air conditioner
.
Liaoning science and technology publishing house
,2002.9.
[2]
Xia Yunhua
,
Qi Hong
.
Use and maintenance of automobile air conditioner
.
Machinery industry press
,2002.5.