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Air Conditioner Selection, Issue #008 -- Icing Is Not Good?
August 01, 2006

01 August 2006 00:00

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Table of contents

  1. Highlight on Air Conditioner Selection Content

  2. Your fourth tip. Tip #0004: About Icing

1. Highlight on Air Conditioner Selection Content

Let's briefly talk about air conditioner charging.

Air conditioner charging can be achieved through three methods.

Subcooling, superheat and using weight measurement.

  1. Charging through subcooling is used for thermostatic expansion valve fitted ACs.

    This method is used as the superheat after a TXV is fixed, through spring and sensing bulb forces

  2. Charging through superheat is used for capillary tube fitted systems, as the factor for throttling is the frictional loss across the tube alone.

    Hence, superheat method is used, such that refrigerant will be completely boiled at the end of the evaporator

  3. Want to be safer and more accurate? Then charge using weight.

    This method will put in, the correct amount required by the system, for proper operation of the AC.

    A scale will be used to measure the amount of refrigerant charged.

    Can be used for both TXV and capillary tube fitted ACs. Peace of mind

Please remember. Refrigerant charging requires a skilled personnel to perform it. But, it's always good to know!

More on how to recharge air conditioner

2. Your fourth tip. Tip #0003: About Icing

Yes, air conditioners are meant to cool, but icing is certainly not good for your AC.

The common places for icing in an air conditioning system are:

  • at the evaporator

  • on refrigerant return line

  • and, after the filter dryer

  1. Icing happens at the evaporator for two main reasons. Due to either, insufficient flow across the evaporator, or insufficient refrigerant.

    The remedies include,

    • cleaning the coil - if dirty,

    • improving the flow across the evaporator - if air flow is insufficient,

    • OR, detect for leaks, and recharge appropriately - if there is not enough charge

  2. Icing at the refrigerant return line, however is a simpler problem.

    It happens due to uninsulated refrigerant return line.

    Search for it, and seal it with synthetic rubber

  3. Filter dryers are located at the liquid refrigerant line.

    This line is supposed to be warm. However, a clogged filter dryer, will create a high enough pressure differential for throttling to occur.

    Hence, you'll see icing (or very cold tube) downstream of filter dryer.

    It's time for a new filter dryer replacement. Don't you think? ;)

Icing problem is not good in an air conditioner operation, as it will not be able to condition air appropriately.

Simple preventive maintenance and periodical checking will be beneficial for you.

Here's a page on general air conditioning maintenance

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All the best and we'll meet again in the next issue!


MJK Nurul Amin,
"Be comfortable"
Chief Editor,

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