A secondary line purging system (40) having a blower (22) for pressurizing a flow of gas and a first pressure sensor (28) for measuring a first pressure of the flow of gas at or near the blower. The system also includes a secondary line (36) communicating with the blower and a subject circuit (32). The system further includes a second pressure sensor (30) for measuring a second pressure of the flow of gas within the secondary line. A valve system (42) is operable in 1) a first mode of operation to isolate the blower from the secondary line and 2) a second mode of operation to permit communication between the blower to the secondary line to purge the secondary line of obstructions with the pressurized flow of gas. A controller (16) switches operation of the valve system between the first mode of operation and the second mode of operation, based on the first pressure and the second pressure.
