Job
Cooling cycle
Once the A/C system is fully charged and free of leaks, it is ready to go. During operation, the compressor lowers the pressure of the refrigerant and thereby lowers the temperature. This refrigerant gas draws heat from the passenger compartment and heat from the running compressor.
The gaseous refrigerant enters the condenser. When passing through the condenser (as a result of vehicle movement or fan operation), this gas is cooled. Now cooled, the gas condenses into liquid and enters the receiver/dryer. The receiver/drier collects the coolant and filters it from any moisture that may be present. Flowing from the receiver, the liquid refrigerant passes through an expansion valve, which converts it into a mixture of liquid and gas at low temperature and low pressure. The cooled refrigerant then enters the evaporator. Getting into the evaporator (inside the car), the refrigerant is exposed to warm air. The refrigerant in the evaporator turns into a gas and absorbs the heat of the air blown by the fan. After complete evaporation, the heated refrigerant gas is drawn through the condenser to the compressor where the cycle is repeated.
The efficiency of any air conditioner is controlled not only by the system itself, but also by external factors such as air temperature, humidity, vehicle speed and the amount of sunlight.
Safety
There are two hazards associated with the air cooling system and they relate to the refrigerant. refrigerant (basic designation: R-12, trade name: Freon, registered trademark of DuPont Co.) - an extremely cold substance. When it enters the atmosphere, it immediately freezes any surface it comes in contact with, including your eyes. Another danger is associated with fire. Normally non-toxic, refrigerant gas becomes highly toxic in the presence of an open flame. A small puff of vapor from combustible refrigerant can be fatal. Keep all flammable items (including cigarettes) away from the air conditioner.
System check
Many problems associated with air conditioning can be avoided if at least once a week, regardless of the season, turn it on for 10 minutes. This will keep the internal parts lubricated and also prevent the hoses from hardening.
Oil leak
Refrigerant leaks show up as oil patches on parts of the system because the compressor oil circulates throughout the system along with the refrigerant. Look for oil stains on all hoses and lines, and especially on hose and line connections. If there are oil deposits, the system may be leaking. A small amount of oil at the front of the compressor is normal and not a cause for alarm.
Checking the compressor belt
Compressor drive belt (air conditioning belt) should be periodically checked for tension and condition. A loose or slipping belt can cause insufficient cooling or damage to system components.
Keep the condenser clean
The condenser is installed in front of the radiator (and is often confused with the radiator when viewed from the front of the car). It serves to remove heat from the air cooling system and cool the refrigerant. Proper airflow through the condenser is essential to the operation of the system. Periodically, inspect the front of the condenser for bent fins or foreign material (dirt, midges, paper, etc.). If the ribs are crooked, gently straighten them with a straight, soft tool such as a thin plank. You can remove the debris with a stiff brush or a water jet from a hose.
Coolant Level Check
If there is a suspicion of a problem, the first thing to do is to check the refrigerant through the sight glass. It is usually located forward of the receiver/dryer in the left front corner of the engine compartment. If you find it, do the following:
1. With the engine running and the A/C on, inside the vehicle, look for coolant flow through the peephole. If the system is operating normally, you will see a continuous flow of clean refrigerant through the peephole, and possibly occasional bubbles if the system is running at high temperatures.
2. Cycle the air conditioner on and off to make sure you see refrigerant. Since the fluid is clean, it is easy to mistake that the system is fully charged. Turn off the system and look through the peephole; if there is refrigerant in the system, you will see bubbles. If you don't see any bubbles when the system is on and cool air is drawn in from the fans, the system is working properly.
3. If you see bubbles in the sight glass while the system is running, there is not enough refrigerant in the system. The only reason for this is the existence of a leak. Operating the air conditioner with insufficient refrigerant charge will damage the air conditioner.
4. Pieces of oil in the eye - a sign of trouble. More often than not, the oil will appear in chunks, although it can also have a solid stream. In any case, this means less cooling and possible replacement of the compressor.
Pressure gauges
Before any attempt at refueling work, you will need a set of air conditioning gauges. The general description of this tool is a set of two pressure gauges and three hoses. By connecting the appropriate hoses to the system, pressure gauges are used to "observations" behind the air cooling system during its operation. The pressure gauge set is also used to drain and prime the system.
WARNING: Wear safety goggles and gloves before repairing!
Always connect and disconnect pressure gauges with the engine off to prevent damage from moving parts. When connecting pressure gauges, first make sure that the valves on them are turned to a position close to off.
Connect the high and low pressure hoses to the compressor test ports.
The center hose is used only when filling and draining the system. For pressure testing, the central hose is not used.