Your overheating!!! try adding water to your cooling system. if that doesnt work it could be your radiator, water pump, or thermostat that is sticking!!!
temp gauge is stuck on hot
A faulty temp sending unit can do that.
Test gauge function with a mechanical gauge to get actual engine temp.
normally the gauge should be in the middle.(between hot and cold) that is concider operating temp.
This would indicate that the system is low on coolant when the gauge is hot. Not enough coolant to service the heater core.
Broken Temp guage
If you don't have a temp. light, or temp gauge, then just install one.
The temp sending unit may be shorted to ground. Unplug the sending unit to see if the gauge drops to cold. If it does, you have a faulty temp sending unit.
Engine is overheating, faulty gauge, faulty temp sensor......
Take wire off temperature sender look a guage. If guage at cool, temp sender needs replacement. If guage still at hot, temp sender wire shorted to engine or vehicle body.
thermostat may be sticking and that cause the gauge to show hot, have it checked soon, you could be headed for bigger problems
Stuck open - no heat from heater, temp gauge hardly moves off of cold. Stuck closed - overheats engine, temp gauge quickly climbs to hot.