Evaporator Core: Description and Operation

Evaporator - 1
When the refrigerant comes from the expansion valve in to, the evaporator, it expands. The pressure in the evaporator is much lower due to the suction effect of the compressor. As refrigerant expands, it becomes gaseous (boils). However, in order for evaporation to take place, heat must be supplied. This heat is taken from the air around the evaporator. The cold air is then blown into the cabin by the fan. Refrigerant is then directed on in gaseous form to the compressor.

The evaporator has fins and a refrigerant manifold. When heat is absorbed, condensation builds up on the outside of the evaporator. This condensation is drained out through a hose in the lower part of the evaporator casing and out into the engine compartment. The drain hose is required in order to protect against dirt and to prevent a higher noise level in the cab and to maintain cooling. In addition, odor may be generated if condensation is not satisfactorily removed.