Ton of Refrigeration

What is Heat & Mode of Heat Transfer?

How to detect leakage in Air conditioner

How to Charge Gas in AC


Central Plant Chilled Water System

Air Distribution Terminal

Selection of Air Handling Unit

Kitchen Ventilation Design

How to Charge Gas in AC

Vacuumization and Then After vacuumization, Gas Charging in Unit

Remember, Air conditioner refrigerant is toxic and can cause frostbite, so, please take the below-mentioned precautions before you begin with AC gas filling.

Safety measures:

Use gloves

Wear protective eyeglasses

Equipment Required

Vacuum Pump with 1-4 horsepower

AC manifold gauge set


And some patience (more on it later) ?

Procedure for AC gas filling

Filling AC gas is actually an easy job with the right tools and safety gear. First, on the air conditioner locate the suction line(low side) and the discharge line (high side). These are located behind a window AC and in a split AC in the outdoor unit The suction line is located above the discharge line and is cool the touch.While the discharge line is warm to the touch. The suction line is used for recharging gas into the AC.

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Service Valve of AC

Unscrew the bolt of the suction line as shown below. Loosen the screw inside with a Torx hex key(as shown in the picture below). This screw acts as a valve, it won’t let refrigerant flow in or out till it is closed. Thus, loosening this screw is important for filling AC gas.

Then remove the bolt on the left and connect the blue hose of the AC manifold gauge to this port. Connect the yellow hose to the vacuum pump. Remove all the air from the system. This step is very important because any moisture inside the compressor will damage it.

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After Vacuumization follow the following steps:-

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Vacuumization is done for removing the unwanted foul refrigerant

Note:- Machine OFF before the vacuumization.

Steps For Gas Charging in AC

Now, make sure all the valves of the AC manifold gauge are closed. Then, connect the yellow hose to the refrigerant tank.

Before opening the tank knob, loosen the yellow hose slightly at the manifold end. Then open the cylinder knob for 1 second and close it. This will remove all the air from inside the pipes.

Now, again tighten the yellow hose.

Now, open the low side knob of the manifold for 3-4 seconds and close it. Then turn ON the AC and wait till the compressor kicks in.

Once the compressor starts, again open the low side valve of the manifold. Keep the valve opened for 4 seconds and close it for 2 seconds. Note where the pressure settles on the gauge once the valve is closed. Keep opening and closing the valve till the pressure settles between 60-70 PSI.

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Gas Recovery from HVAC Equipment or Air-Conditioning Units

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Gas Recovery from AC