Undercharging and recharging the system with refrigerant
As statistics show, the main reason for the abnormal operation of air conditioners and the failure of compressors is improper charging of the refrigeration circuit with refrigerant. The lack of refrigerant in the circuit may be due to accidental leaks. At the same time, excessive refueling, as a rule, is the result of erroneous actions of personnel caused by their insufficient qualifications. For systems that use a thermostatic expansion valve (TXV) as a throttling device, subcooling is the best indicator of a normal refrigerant charge. Weak subcooling indicates that the charge is insufficient, strong indicates an excess of refrigerant. Charging can be considered normal when the liquid subcooling temperature at the condenser outlet is maintained within 10-12 degrees Celsius with the air temperature at the evaporator inlet close to the nominal operating conditions.
The subcooling temperature Tp is defined as the difference:
Tp \u003d Tk - Tf
Tk is the condensation temperature read from the HP manometer.
Tf - temperature of freon (pipe) at the outlet of the condenser.
1. Lack of refrigerant. Symptoms.
The lack of freon will be felt in every element of the circuit, but this deficiency is especially felt in the evaporator, condenser and liquid line. As a result of an insufficient amount of liquid, the evaporator is poorly filled with freon and the cooling capacity is low. Since there is not enough liquid in the evaporator, the amount of steam produced there drops dramatically. Since the volumetric efficiency of the compressor exceeds the amount of steam coming from the evaporator, the pressure in it drops abnormally. A drop in evaporation pressure leads to a decrease in the evaporation temperature. The evaporating temperature can drop to below zero, resulting in freezing of the inlet pipe and the evaporator, and the overheating of the steam will be very significant.
Superheat temperature T superheat is defined as the difference:
T overheating = T f.i. – T suction.
T f.i. - the temperature of the freon (pipe) at the outlet of the evaporator.
T suction - suction temperature read from the LP manometer.
Normal overheating is 4-7 degrees Celsius.
With a significant lack of freon, overheating can reach 12–14 ° C and, accordingly, the temperature at the compressor inlet will also increase. And since the cooling of the electric motors of hermetic compressors is carried out with the help of suction vapors, in this case the compressor will overheat abnormally and may fail. Due to the increase in the temperature of the vapors in the suction line, the temperature of the vapor in the discharge line will also be increased. Since there will be a shortage of refrigerant in the circuit, it will also be insufficient in the subcooling zone.
- Thus, the main signs of a lack of freon:
- Low cooling capacity
- Low evaporation pressure
- High superheat
- Insufficient hypothermia (less than 10 degrees Celsius)
It should be noted that in installations with capillary tubes as a throttling device, subcooling cannot be considered as a determining indicator for assessing the correct amount of refrigerant charge.
2. Overfilling. Symptoms.
In systems with an expansion valve as a throttling device, liquid cannot enter the evaporator, so the excess refrigerant is in the condenser. An abnormally high liquid level in the condenser reduces the heat exchange surface, the cooling of the gas entering the condenser deteriorates, which leads to an increase in the temperature of saturated vapors and an increase in the condensation pressure. On the other hand, the liquid at the bottom of the condenser stays in contact with the outside air much longer, and this leads to an increase in the subcooling zone. Since the condensing pressure is increased and the liquid leaving the condenser is perfectly cooled, the subcooling measured at the condenser outlet will be high. Due to the increased condensing pressure, there is a reduction in the mass flow through the compressor and a drop in cooling capacity. As a result, the evaporation pressure will also increase. Due to the fact that excessive charging leads to a decrease in vapor mass flow, the cooling of the electric motor of the compressor will deteriorate. Moreover, due to the increased condensing pressure, the electric motor current of the compressor increases. Deterioration of cooling and an increase in current consumption leads to overheating of the electric motor and, ultimately, to failure of the compressor.
- Outcome. The main signs of refrigerant recharging:
- Decreased cooling capacity
- Evaporation pressure increased
- Increased condensing pressure
- Increased hypothermia (more than 7 ° C)
In systems with capillary tubes as a throttling device, excess refrigerant can enter the compressor, causing water hammer and eventually compressor failure.
Freon was invented by American chemist Thomas Midgley 90 years ago. Today, almost all climate control equipment works on different brands of freon, as the technicians call it. If it is not enough, then the quality of any split system deteriorates significantly, because the connections and parts begin to freeze. In order to maintain performance at the required level, owners must refuel the air conditioner on time.
- after repair work due to the shutdown of freon lines;
- after installation or dismantling, when the air conditioner is moved to another location;
- due to refrigerant leakage from the circuit.
- two-stage vacuum pump with check valve;
- electronic floor scales;
- open-end wrenches;
- 5-8 mm hexagons;
- manometric manifold with a viewing window, complete with hoses.
- 1. Marriage within the structure itself. During installation, copper pipes can flare. During operation of the device, when freon circulates through them, a leak will occur.
- 2. The amount of gas may decrease during transportation. Dismantling can also cause the loss of freon.
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basic information
If the air conditioner has been repaired or installed, it requires refrigerant charging. This substance usually evaporates at negative temperatures. The price of the service is quite high., therefore, to save money, it is better to solve this problem yourself.
Frequency of refrigerant replacement
Additional filling of freon does not require window and mobile split systems, which are made in the form of a monoblock. They have short tubes mounted inside the case at the factory. Most often, the car cooler loses refrigerant, as it is constantly subjected to vibration. Filling the split system with freon is carried out in the following cases:
If the home air conditioner is new, then there is no need to fill it with gas, because the manufacturer fills the outdoor unit with freon. A conscientious master also comes during the installation or reinstallation of a split system. But often there are failures in their work, and then refrigerant filling is required.
Refueling car air conditioner for 999 rubles.
Signs of lack of gas
Poor operation of the climatic device indicates that the air conditioner needs to be charged with freon split-system. The deterioration of cooling can be caused by various reasons. The following symptoms indicate a lack of gas in the system:
Service ports are located under the cover on the side wall of the outdoor unit. Both highways are connected to them. Freon is supplied in gaseous and liquid state. The diameter of the gas pipe is larger than that of the liquid pipe.
It is recommended that household air conditioners be charged once a year. But if the split system is installed correctly and without any violations, then it can work smoothly for an average of 3 years. If there are reliable connections, a large amount of freon will not leak out. The frequent occurrence of such problems will require disassembly of the joints and checking the quality of the rolling.
Filling materials
To refuel the air conditioner, you should choose the right brand of freon. It is written in the instruction manual of the household appliance. The mark on the required gas is also on the nameplate on the outdoor unit. In such a plate, not only the brand is indicated, but also the rate for refueling, which is considered in kilograms or grams. For self-refueling, you will need the following equipment:
In addition, you will need a special adapter to connect the gauge station to the service ports.
Causes of the leak
For the normal operation of a household air conditioner, a sufficient amount of freon is necessary, with the help of which a constant circulation is carried out. But from time to time, a leak occurs for a number of reasons. This may be due to:
Dismantling the air conditioner with the preservation of freon
Freon filling technology
For a complete replacement, the old gas should be released into the atmosphere, and fresh freon should be poured in. This method is suitable for beginners, as it will be quite difficult to determine the remainder. An experienced master can determine the amount of gas required for refueling. Before starting refilling, the cause of the leak should be determined and eliminated.
An excellent option would be to carry out a pressurization procedure with nitrogen, which is pumped under pressure. In the passport for the air conditioner there is information about the pressure force. Usually it is 25-30 bar. To charge the air conditioner with refrigerant, you must follow the instructions:
The cylinder must be placed upside down on the scales if R410a freon is poured, since it has a liquid state. The collector has a viewing window through which you can see the flow of the substance. When using R22 refrigerant, there is no need to turn the cylinder over.
When carrying out the procedure for charging the air conditioner with refrigerant, it is important not to make a mistake in the sequence of actions and not open the charged circuit. Twenty minutes is the minimum required for vacuuming. During this time, the pump will draw out air and moisture that harm the compressor.
The car air conditioner cools the air entering your car interior and maintains optimal humidity, preventing the windshield from fogging up when it rains.
Evgeniy Blazheevich, a specialist of the AB-TREND autoservice company, shared with the site how to properly maintain and refuel car air conditioners, and also spoke about the most common mistakes made during refueling, leading to expensive repairs.
To maintain the air conditioner in good condition, it must be serviced in specialized services once every 3 years. Cars of earlier years of production (before 2005) must be refueled once every 1-2 years.
A large number of car owners turn to our service with a request to refuel the air conditioner. We have to explain to everyone that the car air conditioner is charged according to the manufacturer's recommendations, and the weight of the refrigerant is strictly regulated. It is impossible to accurately determine how much gas is needed for the full and high-quality operation of your car's air conditioning system without completely pumping out the refrigerant. Sometimes underfilling, or overflowing only 50 grams of refrigerant, you can no longer enjoy the coolness in the sultry heat - the system simply will not work. When refueling the system, the master is guided only by the pressure on the gauges and the air temperature in the car, but it is very easy to make a mistake. In system blockage may be present, which can confuse even an experienced specialist. With further operation under the influence of high pressure, the system will shut down or the refrigerant will be released into the atmosphere.
Often people come with complaints about the lack of cold air, which was recently filled with air conditioning. At diagnostics which we do absolutely for free, it turns out that the pressure in the system does not correspond to the norm, or even completely absent.
How can this be? Everything is simple here. When checking for leaks, many services allow mistake, checking the system with air! There are a number of reasons why air should not be used. The air contains moisture, which is detrimental to your air conditioner. Using professional dehumidifiers it is impossible to dry the air completely, and moisture inevitably enters the system, causing great harm. Another reason why oxygen should not be used is that the oxygen molecule is larger than the refrigerant molecule. It turns out that after refueling, the gas will inevitably leave through possible microcracks, which were not detected during air testing. It is important to take into account the fact that air pressure also increases with increasing temperature. It turns out that the system filled with air may well heat up from a still warm engine and the pressure will increase, thus a small leak will simply not be visible. After such a poor quality check, refueling usually follows, and this is called " money down the drain».
"AB-TREND car service" does not use air for leak testing, but uses NITROGEN. This is a dry gas that does not contain moisture, and nitrogen does not react to temperature changes, which means that if there is a micro leak, then a deviation of the arrow will necessarily appear on the pressure gauge, which will indicate the presence of leaks:
After the leak test, the vacuuming process follows, consisting in removal of air and moisture from the air conditioning system. The air itself can be removed in 5 minutes, but the moisture that inevitably condenses inside the system cannot be completely removed in such a short time. These residues, mixed with oil and refrigerant, form acid which destroys the system from within. Therefore, if you have been refueled or will be refueling an air conditioner in 15-20 minutes, be aware that the refueling technology is violated.
When servicing the air conditioner, only vacuuming should be carried out for at least 20 minutes. If any node was replaced or the system was opened, then the car needs a longer evacuation.
We figured out the vacuuming, it remains only to refuel and everything is ready! But even here it is not so simple. When refueling is added special oil. A dye can be added to it, which will help to find a leak under the light of an ultraviolet lamp. The problem is that, just like in your car's engine, so in car air conditioners, only a certain oil is used that is right for your system. Here is a simple example: we fill up two Citroen C5s of the same year of manufacture. The weight of the charged gas is different, as is the compressor oil. The owners were very surprised that different oils were added to the same cars. In the system, the quantity and type of oil are strictly regulated, their mixing is not allowed. If the service does not have a suitable one, it is better to ask and not add it at all.
As mentioned above, for all cars there are fueling standards that should be followed. After refueling, the system is tested:
The working pressure and serviceability of the fans are checked. The measured temperature of the air conditioner radiator indicates the presence of a blockage in it. The air entering the car interior should be between 8 and 12 degrees.
If you need to get to the evaporator (an important element of the system), it is not necessary to carry out complex and expensive work to disassemble the panel. You can use a special video camera by penetrating anywhere in the duct:
When the air conditioner is running, microscopic drops of moisture, along with bacteria, are carried into the cabin, and then enter the lungs and eyes of the people there. All this greatly increases the likelihood of allergic reactions, influenza and acute respiratory infections. All these troubles can be avoided. It is necessary to carry out periodic disinfection at least once a year with the help of special equipment, after which all pathogenic bacteria and an unpleasant smell in the interior of your car are destroyed:
Entrusting your car to AB-TREND car service, you can be absolutely sure that your car falls into the hands of masters who know their business. The work is carried out on modern German and American equipment, which guarantees accurate diagnostics and refueling of the car air conditioner. European refrigerant and various oils are used. Our organization also provides services for argon welding. Manufactures high pressure pipes and hoses ( RVD) for cars and trucks, various road construction equipment, and industrial equipment.
We we give a guarantee for all our work
Neither I nor the author urge you to repair the air conditioner yourself, but to deal with minor problems and not clap your ears when you are bred for money, this will help you ... Taken from the site http://www.focushacks.com/index. php?l=1
Author Maintenance
Warning: The air conditioning system is under high pressure.
Also, while the R134a refrigerant is not as harmful to the environment as the previous R12, there is still a heavy penalty for releasing R134a into the atmosphere. You should never dismantle your A/C system without proper training and special refrigerant change equipment.
Always wear safety goggles when servicing your air conditioner.
You will be working near a running car with the engine compartment open.
Please take all precautions...
Initial problem solving
If it seems to you that your air conditioner is not working productively, take a thermometer and insert it into one of the cabin air ducts. After starting the air conditioner after a while, the air coming out (if it's not very hot outside) should be between 40*F and 50*F. does not function properly.
With the car running and the A/C on full, open the hood, determine if the engine RPM changes when the A/C is turned on, and observe the A/C pump pulley. It has an electrical clutch, so when it is engaged, the center of the pulley should rotate quickly. It should turn on within 30 seconds or a little longer.
If the pump does not turn on within 90 seconds, make sure your air conditioner is turned on. If the pulley is spinning fast (determined by the center of the pulley) only a few seconds, turns off and after a short pause starts again, this is not a correct cyclic operation.
Any of these problems can be caused by low refrigerant levels. There may be a leak or a more serious problem. You can try to recharge the A/C system with the refrigerant leak indicator.
Leak test and recharge
Necessary tools and materials.
This kit contains 2 fairly large containers of R134a Refrigerant, one of which is with UV dye, it is also equipped with a distributor with a pressure gauge, a nozzle, and a switch: allowing you to change the mode of operation of this device. Also included in this kit is a UV flashlight that makes the UV dye extremely visible without the need for special UV glasses. This kit is available from most auto supply stores and is a universal switchgear that fits most commercially available R134a refrigerant bottles. If the refill kit requires additional assembly, please refer to the attached instructions.
Unfasten the front part of the wheel arch protection (on the side of the bumper), on the passenger side of the car.
Unscrew the 2 plastic screws holding the protection in the wheel well. When the protection is released, take it to the side and lean on the wheel.
4) The charge inlet valve is located on top of the A/C receiver.
5) Connect the distributor hose to the filling port, and measure the pressure. I (He) was told that there is a rule of thumb: With the car not running, the pressure in the air conditioning system should be the same (relatively) as the ambient temperature in Fahrenheit. If it is 80 degrees (26.67*C) the pressure in the system should be around 80 PSI. (= 5.44 atm.)
It’s confusing to put this rule of thumb into practice ...
Ratio *C to *F = 5/9
*F translate to *C= *F–32 x 5: 9
*Ts translate into *F= (*Ts x 9: 5)+32
PSI - Pounds per sq. inch
http://jeep.avtograd.ru/Converters/speed_converter.htm
automatic converter, these very PSI, and not only ...
If it is necessary to add refrigerant, follow the instructions supplied with the top-up kit. (for this kit) You simply measure the pressure when you momentarily press the switch. Further pressing adds refrigerant to the system. Reset the result by pressing the switch key again and check the pressure again.
If after refueling everything worked, it is very good ...
Well, if not...
Advanced Troubleshooting
You can check air conditioner components for leaks; especially if you feel like the air conditioner is gradually becoming less effective. If you added refrigerant with a UV dye, you simply use a UV flashlight, sequentially illuminating all available components on your A/C system, looking for the telltale bright yellow glow. The glow is hard to see in daylight, so wait until evening or check in a dimly lit garage. The fill valve will have some traces of dye after filling it into the system, I used this as an example to show what the dye looks like under U/V. Dye on the filling valve is normal. If you are in doubt that a leak is coming from here, thoroughly clean the fill valve and reservoir, and check again for dye. The most likely places for leaks are joints, and insufficiently clamped connections, directly near the air conditioning pump. Check those areas carefully.
If there are small leaks, you can try to buy a bottle of pump-safe air conditioner leak sealant. It is usually added to the system, as is the coolant, so you don't have to buy another hose if you bought a system like the one I used. If you experience a large leak, or if your leak persists after adding sealant, you should contact a professional mechanic.
There is a high pressure service port (covered with a plastic cover, near the radiator at the top). A high pressure gauge connected to this port, in conjunction with a low pressure gauge on the charge bottle, can diagnose an expansion valve or pump failure. High pressure gauges use special connections, and are not usually sold with a universal A/C recharge kit. Even if you have such a pressure gauge, you still need to know how the pressure should change when the pump is running. When the pump is not running, these two gauges should soon equalize.
There are some defects in the components of the air conditioning system (electrical and mechanical) that are difficult to detect, there are also some air conditioning piping and several components inside the car that cannot be easily checked with dye. U/V dye cannot solve all problems!
There is a small list of symptoms of malfunctions with possible listed problems. Most of these problems require professional service.
Now this is more relevant...
A/C pump does not turn on at all:
*A/C not included.
- Make sure the fan is turned on, the temperature selector is directed all the way to cold, and that the A/C and recirculation lights are on.
* The electrical connector to the electrical coupling of the pump is not connected, the fuse has blown
- Check electrical connectors, fuses, and pump clutch relay
- Check refrigerant pressure, add if necessary
* Air conditioning pressure sensor, wiring to it is damaged or disconnected.
- Check the pressure sensor with a multimeter or ohmmeter, if the circuit is open but the system pressure is good, the pressure sensor may be defective.
- If the sensor is OK, check the connector and wiring
* Defective AC pump clutch
Short cycled pump starts(on and off very fast):
* Refrigerant pressure too low
- Check refrigerant pressure, add if necessary
* Air conditioning pressure sensor, or the wiring to it is damaged
- Visually inspect the wiring to the sensor (on my Focus, it's near the fire wall, on the passenger side, under the carbon filter tank)
* Damaged expansion valve (Located near the air conditioner radiator on the passenger side)
- It is necessary to contact a specialized workshop
* Damaged pump
- It is necessary to contact a specialized workshop
Pump runs but pressure remains too high
* Refrigerant pressure too high
- It is necessary to contact a specialized workshop
do not bleed the refrigerant from the air conditioner.
* Damaged expansion valve
- It is necessary to contact a specialized workshop
* Damaged pump
- It is necessary to contact a specialized workshop
The pump functions, the pressure is good, but the system does not pump cool air into the passenger compartment
* Faulty temperature control mechanism
- Check the temperature regulator, the cables to the switch and to the damper at the other end of the cable (in the center console on the driver's side, below.)
- These components must move when you change the temperature selector. The cable may have become disconnected or the mount is loose. Fix or replace if necessary.
* Clogged or clogged evaporator (meaning inside and outside)
- It is necessary to contact a specialized workshop
The blower fan does not work or only works in some modes
* Blown fuse
- Check Fan fuse (see owner's manual)
* Faulty fan switch (simultaneous failure)
- Check switch with multimeter, replace if necessary
* Faulty fan speed thermistor
*thermal fuse blown, located near the thermistor (then the fan only works at maximum)
Check fan related resistor, replace if necessary
As you can see, air conditioning maintenance is a very complex task, and quite often requires the use of expensive diagnostic equipment. Air conditioner repairers are usually licensed to work with refrigerants. They are also trained to troubleshoot and repair a wide variety of air conditioning system problems and they have all the necessary tools for the job.
Not much time, a couple of cheap measuring instruments, a multimeter and a kitchen thermometer rarely solve the problem. Leaks inside the cabin usually require an expensive refrigerant detector. And this is just one of the many specialized tools that are in use. Air Conditioner systems are also very expensive, so if you are in doubt about the health of your air conditioner, draw your own conclusions.
