1999 gst

temp gauge goes up very high,but does not seem to over heat. seems like sending unit or gauge . When driving gauge seems too stay in the middle, but heater seems hot.How can you test the gauge or the sending unit ?

Chew that back up and spit it out in a paragraph that makes more sense.

Have you checked the cooling system level, not just the overflow tank? Thermostat might be stuck closed. And for the rest, |_eclipse_| said it perfectly, I couldn't understand one damn word of that.