What do you do if your 91 Chevy cavalier spills coolant into your floor board?

Sounds like heater core is leaking and needs to be replaced You probably have a leak in the heater coil of the air conditioning system. You can either get the coolant flow to the heater coil shut off (cheapest) and get along without heat in the car, get the heater coil repaired (iffy), or get it replaced (maybe get a used part from an auto salvage yard.