We recommend vacuuming your condenser every 3 - 6 months. Cleaning the condenser is important for the overall operations of the unit including cooling functions. A dirty condenser may lead to warm temperatures in the refrigerator and freezer. It may also cause the unit to run excessively. It may contribute to condensation or frost inside of the compartments. If the condenser is not cleaned properly it may even cause premature failure of mechanical components in the unit.

 

Condenser Cleaning - All Models

Before cleaning the unit, shut the electricity off at the control panel. When you clean the condenser, wear gloves to avoid injury from the sharp condenser fins. Use a soft bristle brush and vacuum to remove dust and lint from the condenser. To avoid bending the condenser fins, be sure to vacuum in the direction of the fins, up and down. Clean the condenser every three to six months or sooner if you have pets. 600 Series Framed and Stainless Steel louvered grilles: First remove the grille screws located at the bottom of the grille. NOTE: These screws (Phillips head) are accessed with the doors open. Tilt the top of the grille forward and release the springs from behind the grille, then lift off. Overlay Panel Grille: To remove, lift up then pull out at the bottom and down to release from its mounting bracket.

source: http://www.subzero.com/products/detail.aspx?cid=2&productid=17