Temp on dashboard gauge reads cold whether engine is running normal or hot.

Either the thermostat is stuck open (its simple to replace, it may improve heater output during cold weather, improve gas mileage and reduce engine wear if replaced), or the temperature gauge is reading inaccurately perhaps due to a defective sender unit. Most mechanics have a non contact heat measuring gun that measure temperature at the thermostat housing to determine if the thermostat is open or closed.