Chances are the tank on the condenser is the receiver/dryer and the condensor is a subcool unit. Subcools are essentially two condensers in one. Refrigerant enters the first stage of the condenser as a gas, and loses it latent heat due to condensation. The refrigerant then enters the receiver dryer as a liquid where a few things happen. One, the refrigerant is filtered, two any moisture is absorbed and stored by the dessicant, and third it acts as a liquid vapor separator so only liquid refrigerant enters the second stage. The liquid refrigerant now enters the second stage of the condenser where additional heat is removed through conduction and convection. On general I think a subcool improves heat removal over a standard condenser of the same size by about 15%. Manufacturers started using them at least 15 years ago as a way to improve A/C performance of 134a systems. The ones I've seen use what appear to be standard fittings. A subcool would give the best condenser performance per square inch. To tell if it is a subcool unit look at where refrigerant enters and exits the condensr. If both connections are on the condenser it's a subcool. If the exit fitting is on the receiver/dryer it's a standard type condenser. The receiver dryer on a subcool is also generally serviceable. A plug on the bottom can be removed to replace the dessicant when performing A/C repairs.

John