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Author Topic: How to determine how much R134a refrigerant when topping up?  (Read 239 times)

Offline deafgoose

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  • Member Since: Aug 2020
  • Posts: 2
How to determine how much R134a refrigerant when topping up?
« on: August 10, 2020, 10:55:04 AM »

I have an LG LFX25978ST fridge that is low on refrigerant. The compressors run at 25mA and the fridge does get a little cold so I assume there was a slow leak somewhere.

I installed a bullet piercing valve so that I can add some r134a refrigerant but how do I know how much to add?

I watched some YouTube videos that recommend 2PSI on the gauge but I am not sure if that applies to linear compressors.

I know the correct way would be to pull vacuum but I don't have the equipment required.

Offline tcarmen

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  • Member Since: Dec 2018
  • Posts: 127
Re: How to determine how much R134a refrigerant when topping up?
« Reply #1 on: August 13, 2020, 08:54:30 PM »
If the compressor is using 25ma, it's not running.

In any case, this machine has a linear compressor and there's just no way to "top it up" because the compressor speed (and pressure) changes according to the load.


Offline deafgoose

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  • Member Since: Aug 2020
  • Posts: 2
Re: How to determine how much R134a refrigerant when topping up?
« Reply #2 on: August 13, 2020, 09:11:16 PM »
It was cooling a little so today i connected it up to a gauge and it read 0psi.

I added an extra 5psi and now its freezing ice so clearly there is a slow leak somewhere...

Offline tcarmen

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  • Member Since: Dec 2018
  • Posts: 127
Re: How to determine how much R134a refrigerant when topping up?
« Reply #3 on: August 14, 2020, 03:49:27 PM »
Sorry, I have no idea what to tell you except that the leak needs to be found and fixed, and the system evacuated and recharged with the current mount of refrigerant.

It probably also needs a new compressor and evaporator, since the leaks are typically low-side which means the compressor has been sucking up moisture.


Offline Dash

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  • Member Since: Sep 2015
  • Posts: 64
Re: How to determine how much R134a refrigerant when topping up?
« Reply #4 on: August 26, 2020, 10:42:13 AM »
If your house is air conditioned, the low side pressure when refrigerator compressor is running at high speed should be 7 psi.