beer can cold

...as long as that liquid line is filled from 3-4 rows up out on the condenser that is the state that the TXV looks for to operate(if you have it might be cap tubes).if the liquid level(charge) is low that liquid seal where the LL starts coming out of the condenser is changed seeing flashing and gas burps into the TXV....somewhat like a garden hose spray.so as the liquid is metered out into the evap the pressure drops as so does the temperature to give you 40F.typical evap is 18F drop on return air vs supply air taken at the air handler,with 10F rise on the air into and out of the condenser.sounds like it needs a tweek with questionable charges effecting the unit run time(longer) trying to make setpoint