# R410A Charging on Liquid side - Service Port on Gas Side?



## bfletcher7 (Jan 16, 2016)

I'm a DIY and shouldn't be posting but I'm confused by your verbiage; are you describing the liquid line as the low-pressure side and the gas or suction line as the high-pressure side?


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## max_b (Aug 3, 2016)

Yep, that's exactly what I meant. Low pressure / cool / liquid / outgoing (w/ respect to compressor) / thin line is where you supposed to add the refrigerant, but the service port is on high pressure / hot / gas / return / suction line...


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## sidejobjoe (May 30, 2014)

max_b said:


> Yep, that's exactly what I meant. Low pressure / cool / liquid / outgoing (w/ respect to compressor) / thin line is where you supposed to add the refrigerant, but the service port is on high pressure / hot / gas / return / suction line...



The big vapor/suction line is the LOW pressure side.... you should only be charging through this side.... (well, not always but pretty much always). 

You are supposed to charge liquid 410A into the vapor side (tank upside down) BUT you must do it by slightly cracking the valve open so it will change to vapor when it enters the suction line or use a special fitting that will convert it vapor. You MUST, MUST be certain liquid is not entering the low/suction side.... liquids don't compress and your compressor will really not like it if you put liquid into it. 

Or you can just charge with vapor from the tank (right side up), the glide is so, so small you can pretty much treat it like a 500 series refrigerant.


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## max_b (Aug 3, 2016)

Huh... I guess, that's where my disconnect happened, thanks for pointing it out. According to the reading I've done, liquid line should be around 200 psi and vapor return around 400 psi, so I naturally assumed that liquid line is the low pressure line... 

Looking deeper in some diagrams, I see that both, liquid and vapor lines have high / low pressure segments. Thanks for pointing it out!


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## roughneck (Nov 28, 2014)

Most minis have the metering device located in the outdoor unit. 
Most will only have one access port on the service valve, there should be another located on the inside of the outdoor unit for liquid.


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## user_12345a (Nov 23, 2014)

> Looking deeper in some diagrams, I see that both, liquid and vapor lines have high / low pressure segments. Thanks for pointing it out!


If it's a heatpump the indoor section and lines become the high side in heating mode.

There is no should when it comes to pressures, the nameplate has the max design pressures -> what the equipment has been certified for.

Your low side won't be running at 200 psi. Get it up to 200 and it would be grossly overcharged.

It will be likely running in the 35 to 45f degree saturation (boiling point) range, 108 to 131 psi. 

The high side has an even greater range.

The pressures will vary as the operating conditions like return air temperature, outdoor temperature change. You would have to follow the manufacturer's directions to charge accurately-> could be a chart with pressures at given outdoor temps, could be by weight, could be by subcooling or another method. depending on the metering device type.



Google r410a pt chart.


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## sidejobjoe (May 30, 2014)

Yes, I should of noted that my comment was for when it is in the cooling cycle....


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## max_b (Aug 3, 2016)

Folks, thank you very much for setting me straight (and the additional pointers). It all makes sense now. Except for the color theme of the manifold coloring -- blue gauge connects the hot side and red gauge connects to cold? 

Thanks again!


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## user_12345a (Nov 23, 2014)

no technician here, but...

the hose colour doesn't matter.

The large insulated vapour line connects to the low side of the gauges and the small line the high side. it should be marked or for mechanical gauges the low side one will have a lower max pressure.

if the metering device is in the outdoor unit both pipes will be the low side.

you have purge the hoses of air before adding refrigerant to not get air into the system.


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## sidejobjoe (May 30, 2014)

Well, the hose color kind of matters depending on what gauge it is connected to  .... 

Generally blue is suction side and red is liquid side (high pressure). 

I would highly recommend at least watching some youtube videos on how to do this... dangerous things can happen if you don't know what you are doing with a manifold set (e.g. severe frostbite, hoses exploding etc...)


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