Chevrolet: thermostat Chev. Tahoe, chevrolet tahoe, coolent

Question
My 1997 Chevrolet Tahoe needs a new thermostat.  How do I change it?  (The temperature change moves up and down right in front of your eyes and there is no warm air for the defrost/heater)

Answer
Cadle;
  Hi- have you checked all of the hoses,and is the rad. cap ok. as far as the thermastat you must drain the coolent- than take off the water jacket that houses the thermastat , scrape the area clean prior to replacing the new one. than put the new gasket on with sealer and than drop the new one in place and replace the water jacket. and add new coolent. you can go to the library and the tech. books should show you step by step instructions. you can copy them.  ok