【 Weak current College products】 automotive air conditioner refrigeration system and common fault analysis and removal

Summary: this article on automotive air conditioner refrigeration system and common failure made a simple analysis, through the instance to solve troubles. 1. Auto air conditioning failure of simple diagnosis method; 2. Santana air conditioner refrigeration system troubleshooting; 3. instance of car air conditioner maintenance;

Keywords: Auto air conditioning failure analysis and diagnosis and repair

This article on automotive air conditioner refrigeration system and common failure made a simple analysis, through the instance to solve troubles.
1. Auto air conditioning failure of simple diagnosis methods: air conditioner not cold, but do not necessary diagnostic instrument, how the initial diagnosis of air conditioning failure? in Chinese medicine for patients, the doctor is frequently used approach is, in fact, it feels as automotive diagnostic air conditioning failure can also feels for automotive air conditioning. Auto air conditioning pulse is in the air conditioning of high and low pressure pipe, usually open the hood to see. In the check for high and low pressure pipe temperature prior to air conditioning to set to the maximum cooling, air flow, direct firing position, air circulation, A/C switch on. Outlet temperature, according to experience value approximately 5 ℃ or so normal. Up hood fan while running the confirmation e-mail, the compressor is operating. If not running, then release the high-pressure pipe protection cover, gently press on with the benefit of high pressure exhaust thimble, where there is strong evidence of refrigerant in an overflow, the air conditioning system in the circuit of the fault. You should carefully review the air conditioning duct connector grease stains, if it proves to be air conditioning system leakage point exists. Hand to touch the high pressure pipe and low pressure pipe, feel the temperature carefully. In the refrigeration system is working properly, the normal temperature high-pressure pipe is about 50-60 ¡æ, the hand can firmly jerking around 30 seconds, the longest time on hold. Low pressure pipe temperature about 5 ~ 6 ℃, the hand can feel cold hands. If you hand the feel of the air conditioning temperature high pressure tube fits normal, but the car is felt not cool. Certainly there is no air conditioning refrigeration. Problem may be that the air conditioning temperature regulating system. Check heating switch control line is shedding, heating water valve is in the closed position. If you can touch the water valve before and after the normal situation is close to the engine side near the high temperature, low temperature-body side. If incorrect, then adjust the heating switch-off, as effectively as of cooling water to replace heating switch.
　　
Temperature control system of wind Board: adjusting knob feeling temperature is the temperature changes, if not change it may be that the wind Board control cable abscission, as off reinstalling adjustment. Feel the air outlet is large enough, if a small amount of wind is blocked, need evaporator evaporator for clean removal. Touch air conditioning pipes, high-pressure pipe very hot even hot, of course, low pressure pipe is not cool. In this case, you may receive the frequent switching of the compressor. Especially in high speed engine of compressor does not suck. Avoid cannot long high-speed rotation engine, otherwise it will be dangerous.
　　
View the condenser and the water tank and is dirt clogging. If so, clear away the dirt. If true and dirt clogging, view refrigerant observation Windows, see the refrigerant is excessive. phenomenon is able to see the liquid flows, but cannot see any bubbles are proof of the amount of refrigerant charging too much, you need to do a standard notation for taking the time. For high pressure pipe thermal phenomena, but also see below for air conditioner compressor oils and, if it proves that the Compressor Limiter is already high pressure compressor failure, needto be replaced.
　　
Touch air conditioning pipes, high-pressure pipe temperature low and high temperature low pressure pipe. In this case, is the compressor is not valid for the refrigerant cycle, you may need to replace a compressor. If after starting the air conditioning system, two simultaneous operation of electric fan. There is air conditioning pump not suck it may well be the car computer damage should be repaired.
　　
Car air conditioner refrigeration system and common fault analysis and removal are as follows:
　　
① refrigerant leaks without air-conditioning refrigeration system totally blow out, the reason is: no refrigerant in the refrigeration system or refrigerant leakage, refrigerant leakage, it is first necessary to identify leaks and repair it, back in vacuum, perfusion refrigerant.
　　
② refrigeration system jams when compressor, refrigeration system in a site that no serious blocking the flow of refrigerant cycle, you will lose its cooling effect. Then, using pressure gauges measuring refrigeration system high and low pressure side of the pressure value can be found high side pressure value is lower than normal, and low-voltage side of the pressure value into a vacuum, and blocking sites there is a clear difference before and after, which generally appear in the reservoir fluid dryer or expansion valve. Therefore, the available nitrogen to the reservoir fluid dryer or expansion valve of import or export is not blowing, such as open, close, in need of replacement.
　　
③ compressor parts damaged compressor cylinder gasket blowby, into the exhaust valve damage can cause compressor compresses the refrigerant or cannot be compressed. At this point, with pressure gauge measurement of the compressor inlet pressure and discharge pressure, the pressure can be found both in the same or similar, increase engine speed, the pressure value is no obvious change hands touch the compressor inlet and exhaust pipes. You can feel the temperature difference between the two. Occurs when the compressor cylinder gasket blowby, hands to touch the compressor will feel very hot. In this case, the General need to replace the damaged parts.
　　
④ insufficient cooling capacity output result output of insufficient cooling capacity (i.e., blow out of the air conditioning is not cool) reasons and maintenance:
　　
A. refrigerant. When the circulation of refrigerant in the refrigeration system is low, high and low pressure side of the pressure value will be lower than normal, and from observation window to see the bubble flow. At this point, check the system without leakage, you should add appropriate amount of refrigerant.
　　
B. refrigerant. If the charge of refrigerant quantity exceeding the normal capacity of the refrigeration system, will result in increased liquid refrigerant condenser, reducing thermal area, reducing the cooling efficiency. Its main features are: System of high and low voltage side pressure value is higher than normal; hand touchHigh pressure tube, feeling hot; disconnect the air conditioning off about 45s, from observation Windows still see the status of the refrigerant through the foam. At this point, let the low-pressure side you want from the right amount of refrigerant to achieve normal exhaust pressure and temperature.
　　
C. radiation effect. Condenser fins deformation, surface dirt or cooling fan motor speed drops, will make the heat dissipation, resulting in a system of high and low pressure side pressure value is too high and exhaust temperature is too high and the hands touch from the condenser of high-pressure pipe with hot feeling, the need for repair or replacement.
　　
D. expansion valve open too large. Expansion valve warm Pack and the evaporator outlet bandage not good, or expansion valve itself has problems, caused by the expansion valve is opened too large. Performance of high value for the system than the normal low, and low-voltage values than the normal high; from the evaporator from the low pressure pipe temperature than the evaporator surface temperature also cool, need to check the expansion valve warm Pack and the evaporator outlet is packed with good, if necessary, the expansion valve.

E. refrigeration system dirty plugging. Due to the long-term operation of the compressor, mechanical wear of impurities will enable the reservoir fluid dryer or expansion valve slightly blocked, resulting in insufficient cooling capacity output. Performance of low value for the system is too low, reservoir fluids before and after the dryer has a distinct difference in temperature of the pipe, or expansion valve Department frosting, need to replace the reservoir fluid dryer or cleaning of cooling system.
　　
F. There is air in the refrigeration system. Because the air is very difficult to compress into liquefaction of gases, so enter air cooling system, will cause the compressor pressure and discharge temperature increase, resulting in a decline in output of refrigerating capacity. From the observation of the window to see a large number of the State of the refrigerant through the foam. This is due to the vacuum enough, or refrigerant leakage, low-voltage-side caused by refrigeration system into a vacuum and suction air of the outside world. Required system vacuum, reperfusion refrigerant.

2. Santana air conditioner refrigeration system troubleshooting: when connecting air conditioning condenser fan speed switch, but the compressor electromagnetic clutch does not suck, but there is certainly pressure refrigeration system refrigerant quantity. The symptoms indicate that power from x road → fuse FI4 ¡ú air-conditioning switches → outside temperature switch → air conditioning relay coil circuit intact, failures can outside temperature switch and electromagnetic clutch coil circuit. At this moment available DC voltmeter measurement on the first thermostatic switch input docking lines and body voltage between the ground and, if the power supply voltage, and then testing it at both ends insert between the breakover, conduction, breakdown in thermostatic switch; and then use the same method for detection of low-voltage switch, or low-voltage switch on both ends of the Insert short circuit, such as compressor electromagnetic clutch back to work on low-voltage switch, need to be replaced; if still does not work, then further check compressor electromagnetic clutch coil: from batteries directly from a FireWire-compressor electromagnetic clutch coil, compressor electromagnetic clutch should snap-action, otherwise the corrupted, in need of replacement. Put through the air conditioning compressor electromagnetic clutch switch, pull-in, blower can run, but the condenser fan will not turn, coolant temperature reached the value, the fan is running. The above symptom description fuse F23, and cooling fan motor itself is no problem. Therefore, you will need to check air conditioning relays, available DC voltmeter measurement of air conditioning relays outputs and body voltage between ground, if it is discovered that the air conditioning relays can pick-up without output voltage, the air conditioning relay output circuit breaker, welding or replace the air conditioning relays; can also be replaced on the new air conditioning relays for comparison test, if fan operation for air conditioning relays have failed.



3. car air conditioning troubleshooting instances:
　　
High pressure tube oil, dirt clogging, air conditioner not cold a 94, new cars, equipped with air conditioning and automatic WI40 chassis, R134a refrigerant for air conditioning is not used in refrigeration, electromagnetic clutch does not suck, suck-up sometimes, but immediately disengage, does not work. Replace the air conditioning compressor, evaporator and expansion valve, etc., charging refrigerant is still, after the diagnosis is the compressor working poor. Inspection, after starting theengine, open air conditioning electromagnetic clutch pick-up what it is, skip it, and after it several times in a row no longer. Connected to the manifold pressure gauges, test voltage pressure, low pressure side pressure is low, joined the three cans of refrigerants, thereafter can suck a bit long, but still is intermittent suction, disengaged, the car or refrigeration, the pressure is high, the low pressure side around 980.7kPa pressure to 196kPa. After the replacement of compressor, first read fault codes: left temperature setting knob to the red zone and displays the "HI"; the right temperature setting knobs go to blue area and displays "LO"; ignition switch is placed ON, press the AUTO button, the 20s in the press "0" RES and 2s above; the key to the left display panel shows the EO and El, right display fault code 17 and, as a result of the wagon has 06 replaced evaporator, expansion valve and instrument panel, may cause false failure code, so first carry out the code: read fault codes, press the left key, in the left AUT0 display appears the "d" and then pressing the AUTO button on the right, then left the display EO, right display shows 00, failure code cleanup is complete. Remove the reservoir dryer, expansion valves and related high pressure piping, etc., found the condenser to liquid dryer hose connector almost to oil, dirt, jam, pipeline and condenser is scrap metal and black oil, then replace the condenser and high pressure tube, clean the compressor, replace the condenser, high pressure pipe and reservoir dryer; then used high-pressure nitrogen gas blowing low-pressure pipeline, and replace the expansion valve, joined the appropriate dedicated refrigeration oil, then pressed into nitrogen leak detection, refrigerant vacuum, with cooling effect, the test is very good, fault elimination.
　　
Relay resistance value is too large, the air conditioning compressor does not work in a red flag CA7220E-passenger cars-new cars, in use, they soon found thatthe outside temperature is high and the air conditioning use long, air-conditioning compressor does not work. A few minutes after the restart, compressor and air conditioning, and refrigeration systems. This faultPatchy appear frequently, but parking check for a short time but no such fault occurs. The car uses the variable displacement compressor, the throttle fully open and coolant temperature exceeds the specified value and the air conditioning pipes in high and low pressure of the compressor will not work in normal driving, automobile air conditioning refrigeration normal circumstances, the compressor clutch will not be broken. But to judge failed parts, must be in the open air conditioning (cooling) and compressor does not work. Depending on the circumstances, parking start the engine and open air, in a continuous functioning 1 hour later, the compressor has finally stopped working. Immediately on connection compressor clutch line monitoring, find the line no power, disconnect the original relay and compared the new relay, with digital multimeter measurement resistance between the Terminal and found two relays corresponding terminal 75 to U, U to 31 and U to 30 of resistance values are the same, namely 12.7 k Ω, 11.7 k Ω, and 14 k Ω. And terminals U to HLS and 30 to HLS resistance value between the new relay to 129 k Ω, the relay is 143 k Ω. You can determine the original relay section Terminal resistors between is slightly larger values, work long hours, so that the coil heating resistance value changes, the control of the compressor clutch circuit on/off contact disconnected. Pause for a few minutes after the restart the air conditioner properly, because the relay contacts disconnect the cut off current temperature decrease after the relay coil, work and return to normal.
　　
When the replacement of the air conditioning compressor clutch relay, work started normally.
　　
Temperature control switch failure, use the air conditioning is to cook a carxiali usual traffic properly, an open air conditioning and refrigeration, long engine to cook. The thermostat off and loaded on the same. Cooling system cleared the furring, results or similarly cannot use air conditioning.
　　
Vehicle air-conditioning, Cook is certainly not normal. When the car stopped state open air conditioning test, it really soon opened the pot on the water temperature has reached 100 ℃, and car electric fan did not work. Xiali cooling system is a closed-type, liquid cooling, with expansion tank, fan-cooled electric, engine depend mainly on the automobile driving forward. Only when the water temperature is higher than 92 ° c, electric fans to begin work, and when the water temperature is lower than 87 ° c, electric fan and automatically stop work, which depend on the temperature control switch control. This structure is conducive to maintaining optimal water temperature engine, fan or power consumption of the engine. Cooling water to Cook, electric fans, yet did not work, go to the ignition switch ON location, remove the heat sink temperature control switch connectors, and grounding, electric fan start turning on the fan motor is good. Check the fuse is OK, the temperature control switch removal of devolution into in the trough in the multimeter Ω stalls, one table amount received temperature control switch terminals, one table amount received casing, pour cold water in the tub, heated water directly into the water. Normally, when the water temperature is higher than 92 ° c below should be on-87 ± 2 ° c should be disconnected. Do not use thermometers, pour into the boiling water, hands still on temperature control switch failure. Car replacement temperature control switch, use the air conditioning never Cook.
　　
Speed filter inlet off loss, the air conditioning system is not a car xiali cars, powered blower switch and air-conditioner switch, engine idle speed has increased, but the compressor does not work, dashboard on air blowing hot air. Start the engine, put through the air blower switch and switch, engine idling speed increases, the air outlet on the dashboard, it shows the normal Hair Conditioner switches and blower works fine. But at this point the air conditioning compressor does not work, and condenser fan does not rotate. Maintenance, first add the manifold pressure gauge of high and low pressure hoses and refrigeration system corresponding detection valve connected, manifold gauge for high pressure and low pressure table indicates 0.6MPa, under normal static pressure value range. Start the engine, put through the air blower switch and switch. From battery positive pole cited power cable directly through to the air conditioning compressor electromagnetic coils, the pressure plate and closing of the air conditioning compressor electromagnetic clutch is not corrupted, refrigeration system work, the condenser fans are turning to dashboard on the cold wind blowing air also. Further observation of manifold pressure gauge the value of low-voltage and high voltage table indicates the table indicates the values are in the normal range; high pressure pipe liquid mirror without bubbles, confirming sufficient refrigerant in the refrigeration system.
　　
Air conditioning compressor electromagnetic clutch and condenser fans are affected by the car's air conditioning amplifier control. Both are not working properly, its failure causes may be on the air conditioning amplifier. Air conditioning amplifier for electronic, its good works as follows: in the normal operation of the engine, through blower switch and air-conditioning switches, the refrigerant in the refrigeration system with adequate conditions, the air conditioning amplifier first issue enhancing idling speed of the electrical signal to drive the idle vacuum solenoid valve, the engine idling speed increased to l200r/min; at this point the air conditioning amplifier receives the corresponding engine speed pulse signal and the evaporator outlet side of the appropriate temperature for EEG signal and then through to the air conditioning compressor electromagnetic clutch and condenser fan control relay circuit, making refrigeration system into normal working state.

The test, the vehicle air conditioning amplifier works; check air conditioning amplifier wiring harness connector, first confirm that the ignition switch control of power and grounding line are OK, the pressure switch are normal, and then a line-by-line check connector terminals to the sensor and actuator of line breaking between. Discover the original leader is speed filter, which breaking loss air conditioning amplifiers do not have access to the engine speed increases, the air conditioning amplifier the signal can not be connected air conditioning compressor electromagnetic clutch and condenser fan control relay circuit, making the car air conditioning system is not working properly. After speed filter wire welding fine, then reset the installed air conditioning amplifier. Start the engine, put through the air blower switch and air-conditioning switches, with the engine speed increases, the air conditioning compressor electromagnetic clutch pick-up, condenser fan is spinning up, cab dashboard on air blowing cold air, the air conditioning system back to normal work.
　　
Between the inlet valveGap is too small, cooler air conditioner off a car (in-line four-cylinder F22B2-controlled engine) Honda passenger car, use dithering, speed engine idle speed too low, the cold is a conditioner, flame, but the heat is on air conditioning not flame out, fault indicator is not lit. At the time of diagnosis, first obtain fault code, no code output. Check ignition system properly. Test the cylinder pressure normal, estimated at engine internal trouble-free. Then remove the throttle bodies and idle control valves, check, find is rubber objects jams. Will throttle bodies, idle control valve and fast idle valve is clean. After the installation has obviously improved test, but when the vehicle is still dithering, the air conditioner is still out. While the engine temperature, idle more stable, open air conditioning also normal. The car engine idle system consists of three parts: one is the idle adjustment screws to adjust the basic idle; second, fast idle valve, its opening and closing movements and wax-thermostat cooling machine, similar to the contraction of paraffin, bypass plunger airway drive, coolant temperature, paraffin plunger airway swelling, bypass turn; the third is idle control valve, the valve by ECU control, when the air conditioner, power steering pump load increases, as well as headlamps and rear window heater and other inputs used, idle control valve will open, in a timely manner in order to improve the engine speed. The car had been scaled before continuing the valve clearance, check the valve clearance found into the valve clearance is too small, generally only 0.05mm. Cold machine valve clearance standard values should be: 0.23 ~ 0.28mm inlet valve, exhaust valve 0.28 ~ 0.32mm. Original car engines above failure, there are two reasons: first, throttle bodies, idle adjustment screw air channel, as well as idle control valve and fast idle valves are blocked, therefore glioma objects idling excessively low; the other is the intake valve clearance is too small, so that the inlet valve opens in advance, intake and exhaust door at the same time open for longer (valve overlap too large), exhaust gas back into the intake manifold, impact engine work. After valve clearance in accordance with the standard adjusted again, troubleshooting, everything is normal.
　　
High pressure switch work after bad, open air conditioning noise a relay Audi 200/1.8T passenger cars, open air conditioning after heat sink fan speed relay "Squeak" noise. To check, open the Dashboard under guard, start the engine and open the air conditioner, heat sink fan high-speed operation, sound, touch additional relay box, find the fan speed relay-hand, turn off air conditioners, abnormal noise disappear immediately. It can be seen, noise and air conditioning work fan high-speed operation of the circuit. By radiator fan air conditioner and high speeds, high speed relay and has no abnormal noise, engine temperature, high speed and high speed air conditioning pressure difference, only to dual temperature switch F54 and high voltage switchgear FZ3, estimation is the work of bad F33. Check for high voltage switch wiring plug is located in the left front frame, connect the dedicated tool VAGl527 (it is a diode indicates the crafty with pin plug, can puncture the measurement line leather, light-emitting diode is equivalent to a light bulb), start the engine and open the air conditioner, when the radiator fan is not high-speed rotation, indicator light; radiator fan start high-speed rotation, indicator is off, but at this time and no abnormal noise; a radiator fan high-speed rotation, indicator begins after the fast blinking and so at the same time, the heat sink fan speed relay "Squeak" noise. It can be seen, the cause of the failure was the air conditioning high voltage switch in a critical state, and on the technical requirements of this switch is: closed pressure to 1420 ~ 1720kPa, open the pressure is 1170 ~ 1500kPa, open and closed switching point of the pressure difference between at least, to avoid its 200kPa work in a critical state. Replace the pressure switch FZ3, abnormal noise disappear.
　　
Thermostat switch damaged magnetic clutch automatic separation, the compressor stops, and frequently a Samsung Dodge car, when you press the air switch, air conditioning compressor electromagnetic clutch engagement and separation occurs frequently. At the same time, the condenser fans in the coolant temperature is high. Check the refrigerant, pressure switch works, electrical wiring and no circuit breaker and ground short circuit. Computer diagnostic inspection instrument, showing the air conditioning compressor electromagnetic clutch relay failure. You can check that the relay is normal. Short add-high-voltage switch, when the condenser fans start, but the electromagnetic clutch is still frequently engage and separation. Check the evaporator temperature control switch, when shorted thermostat switch, electromagnetic clutch, the air conditioning compressor to work, the air conditioning system can be quickly refrigeration, the fault lines visible temperature control switch is damaged. In the air conditioning compressor operation, common electromagnetic clutch automatic separation, the compressor stops, open the frequent phenomenon, at constant temperature control switch or damage caused by the pressure switch. When the compartment refrigeration temperature falls below the required temperature (evaporator blowing out of the cold temperature is below a defined temperature), thermostat switch function, electromagnetic clutch, the air conditioning compressor stop working, but this failure is rare, often because of the pressure switch failure, so the fault diagnosis more difficult. At the same time, the car is the constant temperature control switch and the air conditioning pipe welding and, therefore, to replace the thermostat switch, you must replace the entire pipe Assembly, the cost is very high. Exclusion, in constant temperature control switch at shorted constant temperature control circuits, such as air conditioning button is pressed, the air conditioning system refrigerant, but constant temperature device cannot control the minimum cooling temperature. In General, hot auto air-conditioning refrigeration, you can also adjust the temperature of the air flow to, so press the treatment process, the car air conditioning to normal use.