I was doing some reading and came across this, Never heard of this, but I guess it makes sense.
"If you cannot measure any subcooling at the
condenser outlet, but you are fairly certain the unit
has enough refrigerant, then check the temperature
of the liquid line leaving the receiver. Some manufacturers
(Heatcraft for one) use the condensing unit
receiver as the subcooler rather than adding tubing to
the condenser coil."