Look at the aircon system as a heat pump. The heat contained in the incoming airflow is transferred to the 'gas' via the evaporator in the cab, so the air is chilled. The heat it contained is pumped away to the condenser, where the fan transfers it back to the atmosphere. It's a loop, hot on one side and cold on the other. To operate correctly, the amount of gas present has to be correct otherwise things can get out of balance and overheating/over-pressurisation can occur. An aircon specialist will check weights and pressures to ensure it's right.
TC
|