How to properly charge your car air conditioner

Car air conditioning creates a comfortable microclimate in the cabin, eliminating the exhausting summer heat. But an air conditioner installed in a car is more vulnerable than similar household devices, as it is affected by shaking while driving, road dirt and harsh chemicals. Therefore, it requires more frequent maintenance and refrigerant top-ups.

How does air conditioning work in a car?

The air in the cabin is cooled due to the presence of a special refrigerant in the closed system of the air conditioner, which, in the process of circulation, passes from a gaseous state to a liquid state and vice versa.

The compressor of an automobile air conditioner is usually mechanically driven by a drive belt that transmits rotation from the crankshaft. The high-pressure compressor pumps a gaseous refrigerant (freon) into the system. Due to the strong compression, the gas is heated to approximately 150°C.

Freon condenses in the condenser (condenser), the gas cools and becomes liquid. This process is accompanied by the release of a significant amount of heat, which is removed due to the design of the condenser, which is essentially a radiator with a fan. During movement, the condenser is additionally blown by an oncoming air flow.

Freon then passes through a dryer, which traps excess moisture, and enters the expansion valve. The expansion valve regulates the flow of refrigerant entering the evaporator already under reduced pressure. The colder the freon at the evaporator outlet, the smaller the amount of refrigerant that enters the evaporator inlet through the valve.

In the evaporator, freon passes from a liquid state to a gaseous state due to a sharp decrease in pressure. Since the evaporation process consumes energy, the freon and the evaporator itself are intensively cooled. The air blown by the fan through the evaporator is cooled and enters the passenger compartment. And the freon after the evaporator through the valve returns to the compressor, where the cyclic process begins anew.

If you are the owner of a Chinese car and you need to repair the air conditioner, you can find the necessary ones in the online store.

How and how often to fill the air conditioner

The type of refrigerant and its quantity are usually indicated on a plate under the hood or in service documentation. As a rule, this is R134a (tetrafluoroethane).

The units produced before 1992 used R12 type freon (difluorodichloromethane), which was recognized as one of the destroyers of the Earth's ozone layer and banned for use.

Freon leaks over time. In car air conditioners, it can reach 15% per year. It is highly undesirable for the total loss to be more than half of the nominal refrigerant volume. In this case, there is too much air and moisture in the system. Partial refueling may not be effective in this case. The system will need to be evacuated and then fully charged. And this, of course, is more troublesome and more expensive. Therefore, it is advisable to recharge with refrigerant at least once every 3 ... 4 years. Before filling the air conditioner with freon, it is advisable to check for leaks in the system so as not to waste money, time and effort.

What is required for freon charging

To fill the car air conditioner with refrigerant yourself, you will need the following equipment:

- manometric station (collector);

- a set of tubes (if they are not included with the station)

- adapters;

— electronic kitchen scales.

If you plan to evacuate the system, then you will additionally need a vacuum pump.

And, of course, a can of refrigerant.

The required amount of freon depends on the model of the air conditioner, as well as on whether partial refueling or full refueling is performed.

Evacuation

By vacuuming, air and moisture are removed from the system, which interfere with the normal functioning of the air conditioner and in some cases can lead to its failure.

Connect the tube from the vacuum pump directly to the air conditioner fitting on the low pressure pipeline, unscrew the nipple and open the valve located under it.

Start the pump and let it run for about 30 minutes, then turn off and close the valve.

Better yet, make a connection through a manometric manifold so that you can control the process according to the pressure gauges. For this:

- connect the pump inlet to the middle fitting of the manometric manifold;

- connect the low pressure pipe of the collector (blue) to the fitting of the low pressure zone of the air conditioner,

- connect the high pressure hose (red) to the discharge fitting of the air conditioning compressor (in some models this fitting may be absent).

Turn on the pump and open the blue valve and the red valve at the gauge station (if the appropriate tube is connected). Let the pump run for at least 30 minutes. Then screw on the pressure gauge valves, turn off the pump and disconnect the hose from the middle fitting of the gauge manifold.

In the presence of a pressure vacuum gauge, its readings after evacuation should be within 88 ... 97 kPa and not change.

In the event of an increase in pressure, it is necessary to check the system for leaks by pressure testing by pumping a certain amount of freon or its mixture with nitrogen into it. Then a soapy solution or special foam is applied to the lines, which will help locate the leak.

After the leak has been repaired, repeat the evacuation.

It must be remembered that a stable vacuum does not guarantee that refrigerant will not leak after it is charged into the system. It is possible to accurately determine whether there is no leakage, only by pressure testing.

How to charge your air conditioner yourself

1. Connect the gauge station by first screwing on its valves.

Connect and screw the blue hose from the blue pressure gauge to the suction (filling) fitting, having previously removed the protective cap. This fitting is on the thicker tube going to the evaporator.

Similarly, connect the red hose from the red pressure gauge to the high pressure fitting (discharge), which is located on a thinner tube.

You may need adapters to connect.

2. If necessary, for example, if a vacuum has been performed beforehand, pour some special PAG (polyalkylene glycol) oil into the oil injector can, which is located on the yellow hose connected to the middle fitting of the gauge station. Oil will be pumped into the system along with freon. Do not use other types of oil!

Read the information on the refrigerant bottle carefully. It may already have oil in it. Then you do not need to fill the oil in the oil injector. Also, it does not need to be added at partial refueling. Too much oil in the system can hinder the operation of the compressor and even damage it.

3. Connect the other end of the yellow hose to the freon cylinder through an adapter with a tap. Make sure the tap of the adapter is closed before screwing onto the thread of the cartridge.

4. Open the tap on the Freon bottle. Then you need to slightly unscrew the yellow hose on the fitting of the gauge manifold and release air from it so that it does not enter the air conditioning system. Bleed air, screw the hose.

5. Install a freon canister on the scale to control the amount of refrigerant pumped. An electronic kitchen scale is fine.

6. Start the engine and turn on the air conditioner.

7. To start refueling, unscrew the blue valve on the gauge station. Red must be closed.

8. When the required amount of freon is pumped into the system, turn off the tap on the can.

Avoid pumping in excess refrigerant. Control the pressure, especially if you refuel by eye when you don't know how much freon is left in the system. For a low pressure line, the pressure gauge should not exceed 2,9 bar. Excessive pressure may damage the air conditioner.

Upon completion of refueling, check the efficiency of the air conditioner, remove the hoses and do not forget to replace the protective caps of the fittings.