The compressor draws in low-pressure, cool refrigerant vapor from the evaporator. This cool vapor is compressed (squeezed) and changed to hot vapor within the compressor, and then forced into the condenser. In the condenser, heat from the refrigerant is radiated into the surrounding air, causing the refrigerant to return to liquid. At 70°F, pressure in the condenser of operating residential refrigerators and freezers ranges between 80 and 160 psi. While a residential refrigeration unit is running, the temperature of the condenser should feel well above room temperature when touched. For optimum efficiency, the condenser should be cleaned every year.
There are two types of condensers commonly employed in residential units: static and fan-forced convection. The static type is mounted on the back of the freezers and refrigerators. It radiates heat through natural convection without the use of a fan. As air in contact with the condenser tubing or fins absorbs heat from the hot refrigerant and becomes heated, it expands and rises, and cooler air occupies its space (see fig. 4a). The fan-forced type is mounted beneath the unit. When the compressor operates, a fan moves air through the condenser tubing fins (see fig. 3). Linted condensers should be cleaned regularly to prevent any restriction of air circulation. When air circulation is blocked by a linted condenser, heat cannot be removed from the vapor refrigerant fast enough to bring it back into its liquid state as it leaves the condenser. Consequently, the evaporator will no longer cool, the unit runs continually, the temperature never drops to a point low enough to satisfy the cold control, and the high-side pressure rises higher than normal, causing the compressor to burn out.
Be sure that enough clearance is always provided for proper air circulation.