No it does not boil over
Question - wickedash, Norfolk, VA, February 26, 2009, 03:18 on 1999 Ford Ranger
Normal operation of the engine warning up is the temp will go higher than normal at first until the thermostat opens then it will return to normal. Better check your coolant level when the vehicle is cool, maybe its a little low and thats why the temp is rising when you turn the heater on.
Go by Autozone and have them put the scanner on it to pull the codes if any