Low coolant? Bad thermostat? Heater core airbound, plugged or restricted? Water pump not circulating coolant?
why does my 2002 chevy cavalier over heat after i change the thermostat and the water pump
Check your coolant level.
thermostat
Muffler Heat Sheild
Heater Airbound? Heater control cable not working? Heater core plugged?
Exhaust components rust out over time due to weather and the heat from the vehicle. On a 2001 Chevy Cavalier, when the muffler strap rusts, welding a new strap in its place will offer a complete and reliable repair.
heat not working
try looking at your resistor pack on the passsenger side lower the blower motor down and there is a heat coil and resistor in there
I'd check the coolant level first, then the thermostat.
Thermostate stuck closed or low on anti-freeze or pluged heater core or bad water pump or the the A.C to heat deverter valve (if equipt) not operating correctly
check cabin filter
To remove the heat shield on a Chevy Cavalier, first ensure the vehicle is parked on a flat surface and the engine is cool. Use a socket wrench to remove any bolts or nuts securing the heat shield to the exhaust system or the vehicle chassis. If the shield is held in place by clips, gently pry them off with a flathead screwdriver. Once all fasteners are removed, carefully lift the heat shield away from the vehicle.