Charging an Air Conditioner: Repairing Compressor Problems

Charging or Recharging Your Unit

Man repairing air conditioner

If the air conditioner at home is acting up, chances are you may need to charge the refrigerant in the unit. They normally do not need frequent charging, the situation would arise only in instances where the refrigerant leaks, some component has been freshly installed or you are assembling a new unit from scratch. Charging refers to the process of adding or removing a fixed amount from the unit, so it can provide uniform cool air throughout the room or house. This also depends on the type you use. A distinction is made between azeotrope and non-azeotrope. The former is a blend which act as a single refrigerant,  whereas the latter do not. Hence, azeotrope can be topped up, but non-azeotrope must be refilled from scratch. Follow the step-by-step instructions given below to find out how you can charge a sluggish air-conditioner.

Step 1

Preliminary work. The first step is to read through the manual to find out what the requirements are, what is the type of refrigerant used and whether this should be left to professionals. Take on this task only if the manual states that it does not require professional expertise and provides help in understanding which technique to be used. Typically, there are three ways in which a unit can be charged depending on the fitting system.

Step 2

For capillary tube fitted systems or in case of inadequate cooling.

Step I - Switch off the air conditioner compressor.

Step II - Fix the cylinder to the centre hose of the pressure gauge.

Step III - Clean or purge the line by throttling the plain gauge regulator and the cylinder regulator. Close the regulators after the cleaning is complete.

Step IV - Remove the safety cap of the unit's service valve and connect the hose from the pressure gauge to it.

Step V - Slowly open the pressure gauge regulator and throttle open the cylinder regulator. Close the cylinder regulator when the pressure has reached the operating pressure applicable to the unit model. Run the unit to check if the cooling is now adequate and the sight glass is not obscured.

Step VI - If the cooling is still insufficient, switch of the unit and repeat the process in step V, until the optimum level of cooling has been reached.

Step 3

For thermostatic expansion valve systems or in case of too much cooling.

Step I - Same as steps I-III above.

Step II - Attach the hose from the compound pressure gauge (in the previous case it was the plain pressure gauge used) to the suction service valve after removing the protective cap from the valve.

Step III - Open the compound gauge regulator slowly, while throttling the cylinder regulator. The pressure applied should be less than the pressure point at which the refrigerant condenses. Close the cylinder regulator when the operating pressure point on the lower side is reached. Run the unit to check if the cooling intensity has come down and the sight glass is clear. Once the optimal low pressure point is reached, it means that enough charging is done and it will now work properly.

Step 4

For a fully emptied unit or a newly assembled air conditioner or a unit where moisture has been removed.

Step I - Switch off the compressor, connect the cylinder hose to the central valve of the pressure gauge and purge the line by simultaneously throttling both the cylinder and gauge regulators. Close the regulators once purging is complete.

Step II - Attach the compound pressure hose from the pressure gauge to the suction service valve.

Step III - Open the compound pressure regulator slowly and fully open the cylinder regulator. Since the it  is being filled from scratch, continue the process until the full required amount has been added to the system.

Step IV - Run the unit, check for the operating pressure, clear sight glass and the superheat status.

"Superheat" refers to the temperature at which it will return back to the compressor in vapor form. The opposite effect of this is "subcool"; which is the temperature at which the refrigerant condenses to a saturated liquid and flows from the compressor to provide the cooling effect.

This kind of repair can be done by the homeowner or by a professional. When deciding, you need to consider that this is a complex process which requires a good understanding of the way an air conditioner works, how the circulation process works and optimal pressure requirements. If any of these sound complicated or tough to you, then it is better to get the professional expertise of qualified technicians to charge the system or repair any leaks. Whatever you decide, your problems will soon be solved and you will be enjoying your cool home in the hot weather.


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