Complex sentence: In a car equipped with air conditioning, outside air is first forced through the air conditioner's evaporator coil, which can be thought of as a heater core filled with very cold gas, which cools rather than heats the incoming air.
Split into simpler sentences: In a car equipped with air conditioning, outside air is first forced through the air conditioner's evaporator coil. This can be thought of as a heater core filled with very cold gas, which cools rather than heats the incoming air.