Overheating problem?? on 1993 Chevrolet S10 Blazer

After driving for 20 mins highway or 40 mins city, the temperature gauge on the dash is all the way up and blinking, however theres no steam and still heat inside the cab, hoping I dont have to replace the rad, temp gauge sending unit works fine and has been tested, any advice is greatly appreciated, thanks!

Asked by for the 1993 Chevrolet S10 Blazer
you need to have the temp confirmed that it is or is not overheating. if it is, you may have done internal damage