If there is liquid leaking into the passenger compartment from the evaporator, what could be a possible cause?

When liquid is leaking into the passenger compartment from the evaporator, a likely cause can be related to the functioning of the air conditioning system and its components. The evaporator is responsible for removing moisture from the air when the A/C system is operational. Normally, condensate that results from this process drains out of the vehicle through an evaporator drain.

If the evaporator drain becomes clogged, condensation cannot escape as intended and can back up, ultimately leaking into the passenger compartment. Additionally, a leaking heater core can also lead to fluid entering the cabin, as the heater core is another component that circulates coolant, and any damage or failure in the heater core can allow coolant to seep into the cabin area.

Given these contexts, both a clogged evaporator drain and a leaking heater core are valid potential causes of liquid entering the passenger compartment. This makes the option that combines both of these causes the correct choice.