The coolant escaping into the passenger compartment couldcontact the driver's feet and injure the driver. Also, steam from the heatedliquid will cloud on the window surfaces and impair the driver's vision andcould result in a vehicle accident.
Visibility — Defroster/Defogger/Hvac System — Heater Core
The end cap connecting the heat exchanger's core to the engine cooling system could rupture and allow hot coolant to escape into the passenger compartment.