If the coolant level is okay, I would suspect a restricted heater core. Try flushing the heater core.
how to replace a heater core on 1994 impala ss
Heater. Core
It is under the hood in the power distribution center.
A 30 amp fuse is required.
It requires a 30 amp fuse.jd
Perhaps a bad fan resistor
Your best bet is to get a Haynes Manual. They make one just for your car.
Behind the heater core in the HVAC assembly. The assembly is behind the radio.
The best thing for you to do is purchase a Haynes Manual that is for your car. They are sold at auto parts stores and bookstores.
How do i remove a heater core to a 1974 chevy impala?
You need to purchase a Haynes Manual for your car. It is very detailed and has pictures also.
Go to a parts house or a bookstore and purchase a Haynes Manual and they have one that is specific to your car.