I'm not familiar with the Corvettes in that series, but in general for
most cars there is a valve somewhere under the hood inserted in the
smaller (1"?) hoses that go from the engine water pump to the heater
radiator core and back (through the firewall) to the front of the
engine. The valve is usually smaller than the palm of your hand, and
probably has 3 hoses attached to it. It may be electrically or vacuum
operated. It's job is to allow engine coolant to pass through a small
heater radiator under the dash when heat is called for, or divert it
right back to the engine via the heater return hose if no cabin heat is
needed, so if it sticks closed, or if it's electrical or vacuum signal
is disrupted (electrical short, vacuum leak, corroded connection,
malfunctioning cockpit control, blown fuse, etc) while it's closed, it
will not open when the driver activates the heater controls. Often these
valves stick closed during the long summer of dis-use. The valve usually
isn't very expensive to replace.

There are other possibilities, of course:

- the heater controls in the dash are malfunctioning and not sending a
signal to that valve, which is more difficult to fix.

- the hot engine coolant is flowing in the heater core, but the heater
blower motor is not operating at all (generally your ears tell you the
blower is/isn't working, or your suddenly colder feet tell you it is);
ie, bad motor or it's not getting electricity or has a bad ground
connection.

- the air vents that direct air through the blower motor and heater core
or to the dash and feet vents are not opening in response to the
settings the driver made (the dash heater controls, or the
vent-actuating solenoids somewhere under the dash are bad).

Start with the diverter valve in the engine compartment.

Manual AC/Heating controls or electronic climate control??
PJ

Have you ruled out the thermostat?

That seems like one of the first things to check, just thought I'd toss
it out there.... :-)

I'd like to hear something on this also.
My '94 doesn't get hot either.
It runs around 190-200f.
It gets luke warm but not hot.
I seeing that it gets luke warm I'd figure that the door is moving.
I wonder if there is a heater hose shut off valve under the hood?
Guess I better break out the service manual and see if there is a flow chart
for this problem.