I have 2 Amana 1.5 ton Copeland Piston condensing units. One for 1st fl and 1 for 2nd fl. The 1stb floor low side is about 70psi @ 78F ambient and the unit is about 20ft level from the unit to the evap. They are both orifice units and I noticed this unit splits off after the orifice into 2 cap tubes but the whole evap does not seem to be sweating. Not sure if 1 cap tube is blocked?
The upstairs unit (same model) is about 50ft run and about 25 ft straight up. They are about 9yrs old. I have always heard a surging sound running up the walls to the attic unit. It also runs and runs but does cool. Just seems to be slow. Could be undersized (Only 1.5 ton 900SF and a lot of sun) so after 9yrs I decided to throw a gauge on. The downstairs unit holds solid at a certain pressure.
The upstairs unit fluctuates about every 3 mins from mid 50's psi to low 70's pgi. The needle is like a pendulum slowly going back and forth over about 3mins. I have a short video i took if you'd like to see it.
So, is this normal for a install going directly up to swing in pressure like this? I am wondering if there could be some non-condensable in the system or maybe a low charge?
I only work in refrigeration and I know if I have a low charge I am in deep vacuum and frozen evap.
Any thoughts? Appreciate it.