1992 Chrysler New Yorker No heat

Try to make sure that you have no air in the cooling system. When safe, remove the radiator cap. Top off with coolant and start the engine. Turn on the heat. Leave the engine running and raise the rpm to 2500 and hold for about 5 seconds. Keep doing that till it reaches normal operating temperature. Keep your eye on the gauge so you don't overheat. When its at operating temp and you have heat at idle then just put the cap back on and you should be good to go.

Ok well my gauges don't work so won't know how many rpm I be at and also put coolant and oil in other day it heated up n ran just fine then the next time I started it the belt came off got it back on n now does same thing no heat and almost over heats