Abstract: A test module is connectable to the suction line of a condensing unit charged with refrigerant, and also electrically connectable to the unit, and is useable to automatically test for proper operation of the unit without having to connect an external test coil thereto or place pressurized nitrogen therein. After the module is connected to the unit, the unit's compressor is started to operate the unit in an “open loop” manner with no refrigerant recirculation therethrough. The module monitors the suction line pressure. If the sensed pressure reaches a predetermined magnitude within a predetermined time after compressor start-up, the module outputs a first signal indicating proper condensing unit operation. Absent this timely attainment of the predetermined pressure, a second signal is generated to indicate test failure. In the case of a heat pump condensing unit, the module tests for proper heating, cooling and defrost operation.

Abstract: A test module is connectable to the suction line of a condensing unit charged with refrigerant, and also electrically connectable to the unit, and is useable to automatically test for proper operation of the unit without having to connect an external test coil thereto or place pressurized nitrogen therein. After the module is connected to the unit, the unit's compressor is started to operate the unit in an “open loop” manner with no refrigerant recirculation therethrough. The module monitors the suction line pressure. If the sensed pressure reaches a predetermined magnitude within a predetermined time after compressor start-up, the module outputs a first signal indicating proper condensing unit operation. Absent this timely attainment of the predetermined pressure, a second signal is generated to indicate test failure. In the case of a heat pump condensing unit, the module tests for proper heating, cooling and defrost operation.