How to Recharge Air Conditioner

There are three different ways of how to recharge air conditioner systems. The methods for this air conditioning maintenance are,

  • refrigerant charging from high pressure side,

  • refrigerant charging from low pressure side,

  • and refrigerant charging using weight


Purpose, do’s and don’ts, and some advice:

Here are some extra tips for you before venturing into how to recharge air conditioner.

  • purpose of refrigerant charging is to add or remove, a specified amount of refrigerant from an air conditioning system, such that you will get comfort air from the air conditioner.

  • contrary to popular belief, refrigerant do not require periodical charging. It is not a consumable item within an air conditioning unit, unless,

    there is a leak within the system,

    you have just changed an air conditioner part, OR

    you are assembling a brand new air conditioner unit

  • refrigerant of 4xx series, e.g. R-404a are non azeotrope type refrigerants, EXCEPT for R-410.

    R-410 is a near azeotrope mixture.

    So, what’s the big deal between azeotrope and non azeotrope refrigerant?

    Azeotrope refrigerants consist of more than one blend of refrigerants, but it acts like a single refrigerant.

    Non azeotrope refrigerants on the other hand, DO NOT act like a single refrigerant.

    The implication is that, the blends will be lost from the system at different proportions due to different boiling temperatures, whenever there is a leakage in the non azeotrope refrigerant.

    Hence, charging of non azeotrope refrigerant can only be carried out from zero to full. Never top up this type of refrigerant in case of leakage.

    Evacuate, and fill to adequate quantity.

    Azeotrope, or near azeotrope blends will act as a single refrigerant, and therefore, may be topped up in case of refrigerant leakage

  • do not overcharge as this will cause compressor damage,

  • do not undercharge

  • correct problems within the system, if subcooling or superheat is inadequate, even if the pressure in the system has reached design state

  • never use open flame to heat up refrigerant cylinders. Use warm water instead

  • recover the excess refrigerant into recovery cylinder, if the system is overcharged

A little more before we go further into how to recharge air conditioner systems.


Ensuring adequate refrigerant charge:

Make sure that,

  • the amount of refrigerant superheat is about 10 oF (5.5 oC), or as per manufacturer’s recommendation, OR

  • the amount of refrigerant subcooling is about 10 oF (5.5 oC), or as per manufacturer’s recommendation, OR

  • the sight glass after (or on) the filter dryer is clear after charging.

    Presence of bubbles means that there is no adequate charging

It’s about time we look into details of "How to Recharge Air Conditioner".


How to recharge air conditioner style 1: From high side:

This method is best used with capillary tube fitted systems.

Other criteria that will require this technique are inadequate subcooling, and to top up refrigerant.

First,

  1. stop the compressor,

  2. know the refrigerant in the system, and get the correct refrigerant to be charged,

  3. attach the refrigerant cylinder or canister to the centre manifold’s hose of the pressure gauge set,

  4. purge the line by throttling the plain gauge’s regulator, and the refrigerant cylinder’s regulator.

    Don’t forget to close the regulators after purging,

  5. attach plain pressure gauge’s hose of the gauge set, to the liquid line service valve of the air conditioning unit.

    Make sure that the protective cap of the service valve is taken out

  6. open the plain gauge’s regulator slightly,

  7. throttle the refrigerant cylinder’s regulator,

  8. close the cylinder’s regulator when the pressure in the high pressure side reaches the design operating pressure,

  9. operate the air conditioning unit,

  10. check the subcooling, and make sure that the sight glass is clear,

  11. stop the air conditioning unit if the subcooling is inadequate. Repeat steps (7) to (10) until the charging is adequate

How to recharger air conditioner from high pressure side. Courtesy for condenser picture: Bryant Air Conditioners
Courtesy for condenser picture: Bryant Air Conditioners


How to recharge air conditioner style 2: From low side:

This method is best used with thermostatic expansion valve fitted systems.

Other criteria that will require this technique are inadequate superheat, and to top up refrigerant.

First,

  1. stop the compressor,

  2. know the refrigerant in the system, and get the correct refrigerant to be charged,

  3. attach the refrigerant cylinder or canister to the centre manifold’s hose of the pressure gauge set,

  4. purge the line by throttling the compound gauge’s regulator, and the refrigerant cylinder’s regulator.

    Don’t forget to close the regulators after purging,

  5. attach compound pressure gauge’s hose of the gauge set, to the suction service valve of the air conditioning unit.

    Make sure that the protective cap of the service valve is taken out

  6. open the compound gauge’s regulator slightly,

  7. throttle the refrigerant cylinder’s regulator.

    The pressure within the system shall be less than the condensing pressure of the refrigerant

  8. operate the air conditioning unit,

  9. close the cylinder’s regulator when the pressure in the low pressure side reaches the design operating pressure,

  10. the charge should be adequate once the design pressure on the low side is reached, but it is good to check the superheat, and make sure that the sight glass is clear

How to recharger air conditioner from low pressure side. Courtesy for condenser picture: Bryant Air Conditioners
Courtesy for condenser picture: Bryant Air Conditioners


How to recharge air conditioner style 3: Using weight:

This method is used to charge refrigerant to an evacuated, or newly assembled, and moisture removed air conditioning unit.

The steps,

  1. stop the compressor,

  2. know the refrigerant to be handled by the system, and get the correct refrigerant to be charged,

  3. attach the refrigerant cylinder or canister to the centre manifold’s hose of the pressure gauge set,

  4. purge the line by throttling the compound gauge’s regulator, and the refrigerant cylinder’s regulator.

    Don’t forget to close the regulators after purging,

  5. attach compound pressure gauge’s hose of the gauge set, to the suction service valve of the air conditioning unit.

    Make sure that the protective cap of the service valve is taken out

  6. put the cylinder on weighing scale,

    OR

    get adequate number of refrigerant canisters to charge the system

  7. open the compound gauge’s regulator slightly,

  8. throttle the refrigerant cylinder’s regulator,

  9. operate the air conditioning unit,

  10. close the cylinder’s regulator when the correct amount of refrigerant is added to the system

  11. check the superheat, operating pressure, and make sure that the sight glass is clear

How to recharger air conditioner using weight. Courtesy for condenser picture: Bryant Air Conditioners
Courtesy for condenser picture: Bryant Air Conditioners

That’s about it on how to recharge air conditioner systems. Remember that a leak free system do not need regular refrigerant charging.



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