Air conditioning maintenance refrigeration system failure:
1. Normal parameters of refrigeration system;
Before air-conditioning maintenance, make clear the maintenance parameters of air-conditioning, such as current and pressure [high and low pressure], the operating frequency of compressor tested by voltage inverter, outlet temperature, etc. As described in detail below.
1. Operating state parameters during refrigeration
1. The normal low pressure of the refrigeration system is between 4 and 6 kgf/cm2.
2. The normal high pressure of the refrigeration system is between 16- 19kgf/cm2.
3. The air outlet temperature of air conditioner should be between 12- 15C.
4. The temperature difference between the air inlet and the air outlet should be greater than 8C.
5. When the outdoor temperature is 38C during shutdown, the equilibrium pressure is about 10kgf/cm2.
[The above parameters are related to indoor and outdoor ambient temperatures, and should be analyzed in detail during maintenance]
6. The shell temperature of the fully enclosed reciprocating piston compressor is about 50 C. 。
7. The shell temperature of the fully enclosed reciprocating scroll compressor is about 60 C. 。
8. The shell temperature of the fully enclosed piston rotary compressor is about 50 C. 。
9. Usually, the temperature of low-pressure pipeline is around 15C. Under normal circumstances, the low-pressure pipe should be dewed but not frosted, as shown by frosting.
The system is short of fluorine or blocked.
10. The temperature of the exhaust pipe is usually between 80 and 90 degrees Celsius. If the temperature is too low, the system is short of fluorine or blocked, such as temperature.
If it is too high, there is air or compressor mechanical failure in the system.
1 1. Freon can be added according to the condensation condition of the suction pipe, and the suction pipe may frost if the amount of Freon added is not enough.
When the upper part of the suction pipe of the compressor is frosted, it shows that the fluorine addition is moderate.
12. Generally, the shell temperature of fan motor shall not exceed 60 C. 。
13. The indoor drainage pipe should be drained after the air conditioner runs for one hour.
14. The sound of refrigerant flowing in the capillary can be heard indoors or outdoors. If you can't hear the sound of flowing, it means cooling.
There is something wrong with the air conditioning maintenance system.
2. Heating working state parameters
1. The normal low pressure of the refrigeration system is between 4 and 6 kgf/cm2.
2. When heating in winter, the normal high pressure of refrigeration system is between15 and 22kgf/cm2.
3. When heating in winter, when the ambient temperature should be 10', the system equilibrium pressure should be about 6kgf/cm2.
4。 When heating in winter, the outdoor radiator will frost when the ambient temperature is too low.
5。 When fluorine is added in winter, the pressure at the bottom of the refrigeration system should not exceed 3. 5kgf/cm2 is suitable.
6。 When heating in winter, the outlet temperature of heat pump air conditioner should be between 35~42'C, and the temperature difference between inlet and outlet should be greater than15' C.
[The above parameters are related to indoor and outdoor ambient temperatures, and should be analyzed in detail during maintenance]
7。 When heating in winter, the outlet temperature of electric air conditioner should be between 30~45'C, and the temperature difference between inlet and outlet should be greater than15' C. ..
8。 When heating in winter, the temperature of compressor shell should be higher than that when cooling 10. Around C.
9。 When heating in winter, when the air conditioner is in defrosting state, the compressor runs normally, and the indoor and outdoor fan motors should stop running. Frequency conversion air conditioner has the function of defrosting without stopping.
10。 When fluoride is added in winter, the air conditioner should be placed in a refrigeration state, and it is best to use quantitative filling. If conditions do not permit, fluoride can be added by measuring the high pressure of the system, which generally does not exceed 20kgf/cm2.
1 1。 When heating in winter, when the ambient temperature is lower than -5' C, the heating effect of air conditioning will be obviously reduced, and outdoor opportunities will be frosted.
12。 During heating operation, there should be no temperature difference at both ends of one-way valve. If the temperature difference between the two ends indicates its internal leakage.
13。 When the air conditioner is in defrosting state, the reversing valve is closed, and the outdoor machine will make airflow sound; Such as reversing valve
If the coil is broken and there is no such airflow sound, it means that the reversing valve is faulty.
14 When heating in winter, if the outdoor ambient temperature is high, outdoor opportunities will drain water.
1, the reason for the increase of exhaust pressure
The exhaust pressure of refrigeration system corresponds to the condensation temperature, and the exhaust pressure has a great relationship with the flow and temperature of cooling medium, compressor efficiency and cooling load.
(1) Reasons for the increase of exhaust pressure under refrigeration.
1 Too much air or refrigerant in refrigeration.
2 outdoor fan motor speed is low or not running.
3 outdoor temperature or fan heater is too dirty
4 Electronic expansion valve opening is too small
5 One-for-two air-conditioning indoor stand-alone machine does not work
6 The refrigeration system is partially blocked. (Dirty blockage, ice blockage, oil blockage, angle valve not fully opened)
(2) The reason for the rising exhaust pressure in heating state.
1 Too much air or refrigerant in the refrigeration system.
2 indoor radiator or filter screen is blocked
3 indoor temperature is high or the filter screen is blocked
4 indoor fan motor speed is low or not running.
5 Mechanical failure of indoor fan motor leaves stuck.
6 Electronic expansion valve opening is too small
7. This system is semi-closed. (i.e. dirty blockage, ice blockage, oil blockage and angle valve not fully opened)?
Second, the cause of the exhaust pressure drop
refrigeration system
Second, the cause of the exhaust pressure drop
The exhaust pressure of the refrigeration system corresponds to the condensation temperature, and the suction pressure also corresponds to the condensation temperature.
Causes of exhaust pressure drop in air conditioning maintenance refrigeration system;
1 The refrigeration system is short of fluorine.
2 indoor fan motor speed is low or not running.
3 compressor exhaust efficiency is reduced
4 leakage of four-way reversing valve or electromagnetic bypass valve
5 The refrigeration system is blocked or the pressure valve at the bottom of the outdoor unit is not opened.
6 Frequency conversion compressor does not increase the frequency
Second, the reasons for the decrease of exhaust pressure in heating state:
1 internal leakage of four-way reversing valve;
2 Check valve leaks or auxiliary capillary is blocked.
3 the refrigeration system is short of fluorine
4 outdoor ambient temperature is too low
5 The outdoor unit does not defrost or the defrosting is not clean.
6 outdoor radiator is too stolen
7 compressor exhaust efficiency is reduced
8 outdoor fan motor speed is low or not running.
9 Frequency conversion compressor does not increase the frequency
Third, the reason for the increase of inspiratory pressure
The suction pressure of the refrigeration system corresponds to the evaporator temperature, and actually the suction pressure also corresponds to the exhaust temperature. That is, the higher the suction pressure, the higher the discharge pressure, and vice versa.
(1) The reasons for the rising suction pressure of the refrigeration system are as follows:
1 The opening of electronic expansion valve is too large.
2 outdoor ambient temperature is too high
There is excessive air or fluorine in the system.
4 outdoor fan motor speed is too low or not running.
5 outdoor radiator is too stolen
6 compressor suction and exhaust efficiency is reduced
(2) The reasons for the rising suction pressure of refrigeration system are as follows:
1 The indoor radiator or filter screen is too stolen.
2 The indoor fan motor does not rotate or stop.
3 Internal leakage of four-way reversing valve
4 outdoor ambient temperature is too high
5 the electronic expansion valve is too open.
There is excessive air or fluorine in the system.
7 compressor suction and exhaust efficiency is reduced
Four reasons for the decrease of suction pressure
The reasons for the decrease of suction pressure in refrigeration state are as follows:
1 There is too little refrigerant in the refrigeration system.
2 compressor suction and exhaust efficiency decreased?
3 indoor radiator or filter screen is too blocked.
4 Indoor ambient temperature is too low
The electronic expansion valve is too small.
6 indoor fan motor speed is too low or not running.
7 Half-blockage of refrigeration system (theft blockage, ice blockage, oil blockage)
(2) The reasons for the decrease of suction pressure in heating state are as follows:
1 The system is blocked internally or there is too little refrigerant.
2 compressor suction and exhaust efficiency decreased?
The electronic expansion valve is too wide.
4 outdoor ambient temperature is too low
5 outdoor unit does not defrost or the defrosting effect is poor
6 the fan of the external machine does not turn or the radiator is too stolen.
7 The external fan speed is too low or stopped.
8 Internal leakage of reversing valve or bypass valve
The reasons for the temperature change of the refrigeration system are as follows:
The evaporation temperature of the refrigeration system corresponds to the suction pressure and the condensation temperature corresponds to the exhaust pressure. By analyzing the change of suction and exhaust pressure, it is equivalent to analyzing the change of evaporation temperature and condensation temperature.
1 The suction temperature of the system is high, and the suction pressure is correspondingly high.
2 The bottom suction pressure corresponding to the bottom suction temperature of the system
3. Large system flow and low suction temperature.
4. The system flow is small and the suction temperature is high.
5 The capillary of the system is certain, too much refrigerant is injected, and the suction temperature is low?
The capillary of the system is fixed, the refrigerant injection is too small, and the suction temperature is high.
7 system electronic expansion valve is too small, low suction temperature?
8. The electronic expansion valve of the system is too large and the suction temperature is high.
9 The condensation temperature of the system is high, and the exhaust pressure is correspondingly high.
The condensation temperature of 10 system is at the bottom, and the exhaust pressure is also at the bottom.
Essentials of air-conditioning troubleshooting (my experience in air-conditioning troubleshooting for many years)?
Key points of "asking, smelling, listening and diagnosing" and "looking, smelling and testing" in color TV maintenance. What are these five points:
Look; Whether the power supply voltage is normal, whether the radiator is too dirty, whether there is oil stain on the connector, whether the compressor suction pipe is dewed, and whether the fault points are distinguished by fault codes.
Listen; The compressor and fan motor are operating normally. No, when the four-way reversing valve changes direction, the airflow sound is normal. No, the noise of the external machine is normal. No, is there a sound-absorbing capillary when the reversing valve works? Is the refrigerant flow in the expansion valve normal?
Touch the fan motor, the compressor shell temperature is normal, the capillary surface temperature is normal, the compressor suction and exhaust temperature is normal, the four connecting pipes of the four-way reversing valve are normal, and there is a temperature difference between the two ends of the one-way valve.
Second, the refrigeration system failure causes
Refrigeration When the refrigeration system fails, it is generally impossible to directly observe the location of the failure, so it is necessary to compare the high and low pressure values of the refrigeration system with the normal values, and then analyze the cause of the failure.
Is the temperature of the plug high current connector normal? Is the temperature of IPM power module shell normal?
Whether the smell of refrigeration oil is normal and whether the electrical components are burnt.
Measure whether the inlet and outlet temperature of air conditioner is normal, whether the suction and exhaust pressure of compressor is normal, whether the operating current of air conditioner is at load voltage and whether it is normal.