LeftieBiker wrote:In very cold weather, moisture would build up in the cabin.
Moisture (and heat) is removed when the air is blown over the cold coils of the evaporator. The moisture condenses and is allowed to run off.
The heat in the air is transferred to the evaporator coils (exposed to outside air) via the refrigerant. The OP suggests instead of letting that heat escape, route the refrigerant instead to a set of evaporator coils inside the car. This would conserve the cabin heat. The evaporator coils would still get cold, and still remove moisture. Just as an in-house dehumidifier removes humidity even though both its evaporator and condenser are in the same airspace. It neither heats nor cools.*
*-- well actually it heats a bit, due to dissipating the work of the electric motor and electrical resistance.