I just had a yearly "checkup" on my heatpump (Trane XL15i), and they said the subcool was high (28), which does seem high (here are all the "deets")
OD Temp: 42
ID Temp: 69
SL Temp: 40
DL Temp: 75
Head PSIG: 330
Suction PSIG: 66
So, they suggested that the Filter drier is most likely clogged. Which, I'm cool with paying to have them replace, that's fine. My question is, looking around online, this would seem to be the opposite of the case. Too high a subcool, from what I can find, generally means overcharged system doesn't it? And as you'll note below, last year was fine, and refrigerant doesn't just osmose into the system, so the likelihood of an overcharge seems remote.
Could it be that the guy just didn't let the system run long enough, or...?
Looking at the numbers from last year, my subcool was 16 on a 48F day, which apparently is right where it should be.
I'm obviously not looking to do this myself, and I have a tech scheduled to come out and do a real diagnosis on Monday, but I want to make sure I don't get talked into something that just doesn't make sense. Any help would be appreciated, and better would be an explanation for why this is either right or wrong.
Thanks very much! Let me know if you need additional data.