Where is the heat exchanger located on a Carrier WeatherMaker 8000 gas furnace so I can check if it is cracked?

Are you having issues that concern you? Headaches, drowsiness? You have to remove the front of the burner plenum so you can see the exchanger. How are you going to check for cracks? Many are not visible. There are 2 good ways to check. One is a water test where the outside of the exchanger is sprayed with a surfactant and then the inside is inspected for leaks and the other way is to block the vent, inject smoke into the burner plenum and if you see smoke coming out of the plenum, the exchanger is cracked. Another way is to test for Carbon Monoxide(CO) in the house air using test equipment. CO can kill you, it is an odorless and colorless gas.