General information about refrigerant R-134a
Since R-134a is a fluorinated hydrocarbon (HFC, in which chlorine atoms are replaced by hydrogen atoms), it does not have a harmful effect on the ozone layer of the atmosphere. To protect the ozone layer, Mitsubishi Motors Corporation recommends using special devices for recycling R-134a.
Refrigerant R-134a is a transparent, colorless substance, both in the liquid and gaseous phase. Since the boiling point of the refrigerant at atmospheric pressure is -29.8°C, then under normal conditions of temperature and pressure it is in a gaseous state. This gas is heavier than air, it is not flammable and is not explosive.
Security measures
Caution: Incorrect maintenance may result in damage to or unintentional deployment of the Supplemental Restraint System (SRS). Before performing maintenance or repair work, read and follow the instructions in the relevant section in the chapter "SRS passive safety system".
1. Maintenance of the air conditioning system.
Caution: Always wear safety glasses when servicing air conditioning systems.
At normal temperatures and atmospheric pressure, the evaporation rate of liquid refrigerant R-134a is so high that it freezes any object that comes into contact with it. Therefore, special care must be taken when handling liquid refrigerant to prevent it from coming into contact with your skin and, especially, your eyes. Always wear safety glasses when servicing the cooling part of the air conditioning system. Also, keep a bottle of clean, sterile mineral oil (petroleum jelly) at hand. If liquid refrigerant comes into contact with your eyes, rinse them immediately with a few drops of mineral oil. The oil quickly absorbs the refrigerant. Then rinse your eyes with plenty of cold water. Even if the irritation stops after these procedures, seek immediate medical attention.
2. Refrigerant charging.
Caution: Do not heat the refrigerant above 40°C.
When filling the system with refrigerant, in most cases it is necessary to moderately heat the refrigerant cylinder to create increased pressure in the cylinder compared to the pressure in the air conditioning system. For this purpose, a large container filled with warm water with a temperature of no higher than 40°C is usually used. It is prohibited to use a blowtorch, burner, etc. to heat the refrigerant cylinder, since in this case the pressure and temperature of the refrigerant may exceed the maximum permissible temperature specified above. Do not weld or wash with hot steam parts located in the immediate vicinity of the components and hoses of the air conditioning system.
The amount of refrigerant is 550±20 g.
3. Topping up with refrigerant.
Caution: When filling the air conditioning system, the refrigerant cylinder must be in a vertical position.
(The article is based on data from the website: «MITSUBISHIMAN»)
If the refrigerant cylinder is lying down or the valve is turned down, the refrigerant in the liquid phase will enter the air conditioning system and damage the compressor.
4. Search for refrigerant leaks.
Caution: Always carry out work on the air conditioning system in well-ventilated areas.
Note: To check for gas leaks in the air conditioning system, a special R-134a refrigerant leak detector should be used.
5. Features of polished and chromed coatings.
Caution: Avoid allowing liquid refrigerant to come into contact with polished metal surfaces.
When liquid refrigerant comes into contact with polished and chromed surfaces, they lose their shine and become dull, and the combination of refrigerant and moisture can lead to the appearance of corrosion spots on the entire surface of the metal.
6. Replacement of parts.
a) Before removing parts, remove the refrigerant from the system.
b) The openings of the disconnected parts should be immediately closed with plugs to prevent moisture, dust and other contaminants from entering.
c) Do not store the condenser or receiver-drier without plugs.
d) Before installing a new compressor, remove the refrigerant through the charging valve, otherwise when removing the plug, the compressor oil will leave the system along with the refrigerant.
d) It is prohibited to use a blowtorch to bend or extend pipes, as a layer of oxides will form on the pipes, clogging the system.
e) When tightening the nuts, use two wrenches to prevent the pipes from twisting.
g) Use O-rings and seals designed for R-134a refrigerant only.
Working with tubes, hoses and connections
1. Kinking of hoses or sharp bends in air conditioning system tubes significantly reduces the efficiency of the system.
2. When the air conditioner is operating, high pressure is created in the system, so special attention should be paid to the reliable tightening of all connections. If the air conditioning system is depressurized (during replacement or repair of parts and units), foreign substances and moisture may enter it.
3. The following precautions must be observed when servicing and repairing the air conditioning system.
a) Before disconnecting any connection of the air conditioning system (or replacing its parts), it is necessary to completely evacuate the refrigerant from the system. Loosen the connections of the air conditioning system carefully, even after evacuating the refrigerant from the system. If signs of increased pressure appear when loosening any fitting, wait and very slowly release the pressure.
b) Never attempt to re-bend already bent tubes during assembly. When laying flexible hoses, observe the rule that the bending radius of the hose should be at least 10 hose diameters.
c) Sharp bends in hoses reduce the volumetric flow of refrigerant. Flexible hoses should not be run closer than 80 mm from the engine exhaust manifold.
d) It is necessary to check the condition of flexible hoses and their correct installation at least once a year.
d) All standard air conditioning system connection O-rings are not reusable.