 Coolant will spray directly into the passenger compartment followed with white colored smoke, a significant driving hazard.Because the heater core is usually located under the dashboard inside of the vehicle and is enclosed in the ventilation system's ducting, servicing it often requires disassembling a large part of the dashboard, which can be labour-intensive and therefore expensive.Since the heater core relies on the coolant's heat to warm the cabin air up, it obviously won't begin working until the engine's coolant warms up enough.