Arrived on site to perform diagnostic on unit. Upon arrival, homeowner mentioned another company was out to diagnose, and told him it was a bad heat exchanger. Advised I would have to do my own diagnostic, but homeowner was under the impression that I was only coming out to verify wether the the heat exchanger was good or bad. After speaking with management, it was approved it go ahead and pull the heat exchanger as part of the diagnostic fee, even though there is usually an extra charge for the added labor. Unit has sever roll out burn marks all over the heating compartment. This is usually indication that there is an issue with venting. Per homeowner approval, went ahead and pulled heat exchanger and performed water leak test. Thoroughly inspected all chambers of heat exchanger and it does not appear to be cracked at this time, although there is a very evident crack starting to form at top most chamber. Showed homeowner findings. Put system back together and cycled heating. Shut syst