Subcooling Question

[Ant27]

Could anyone answer this question please as I am a bit stumped?
How can I check the correct saturation temperature for subcooling if my high side gauge is on the liquid line service port just after the expansion device? That won’t give me the correct pressure reading will it?? The unit is an LG UM42. R410a.
Thanks in advance

[seanf]

There may be another service port for the high side within the outdoor unit. Or there may be a way to get a reading from a pressure transducer, Ive not done much with LG AC so Im not sure.

A service port after the expansion device wont give the correct pressure for calculating subcooling. But if the unit is reverse cycle for a heating mode you may be able to use that port then.

[Glenn Moore]

Measure the pipe surface temperature of the condenser mid way through the condenser circuit, this will give you the saturation temperature for the discharge of the system , then measure the pipe temperature at the outlet of the condenser, the temperature difference is the degree of sub cooling . Using a comparator once you have the saturated discharge temperature for R410A then you can work out the discharge pressure. Easy

[nike123]

You cannot check subcooling at split-system refrigerant charging/evacuation port in cooling mode! You can only check superheat!
In heating mode, at that point, you can only check total superheat.
Corect charge is checked by weighing refrigerant.
Corect operation is checked by measuring air properties!
For other measurments, you need to install test points and/or use thermal camera and termocouples at apropriate system points to obtain temperature diferences.