Leak in heater core
1991 Corsica its under the trottle body
Green coolant (prestone, etc)
Place something to catch the engine coolant beneath your 1990 Chevy Corsica radiator. Remove the radiator drain plug with a 9/16 ratchet. The engine coolant will drain out.
Mine does not. Perhaps you a low on coolant.
your heater core is leaking
under the kick panel passenger side
If the coolant fan does not operate on a Chevy Corsica, it is likely that a fuse is out. There could also be a mechanical defect in the fan or wiring.
inside dashboard on passenger side
In the compartment between the driver and passenger seats is a switch
The 1994 Chevy Corsica fan relay switch is located beneath the passenger side dashboard. The fan relay switch should be labeled as such.
Under dash, near firewall, passenger side.
Passenger side top of engine, in front of the alternator.