My temp shot up to the red the other day. So far I have changed the thermostat and fixed the damaged wiring to the sensor (yellow). I am not sure where to check or even how from here. There is no apparent decrease in coolant leaks. The interior heater when turned on all the way to hot, no longer blows heat. Is this most likely a blockage in the system somewhere? Water pump is only two years old with little miles on it.

Is a professional shop the way to go?? The temp guage goes quite quickly into the red, and stays there (no quirky fluctuations), so I am not driving it anywhere.