TOPIC: Client HVAC Question

Ok, I'm chatting with a client about her furnace...she says it is making a "clunk" when the  burners shut off and the blower is finished with it's cycle.  Now, I'm know I'm going to be mocked and ridculed, but I can't remember what the cause of this is...help?? 
:-\ :'( : ;D

No ridicule here just no answer to that question without sitting in front of the furnace could be to many things. such as a loose blower wheel on the motor shaft, gas valve improper shut down, heat exchanger over heat, heat exchanger cooling down to fast with the introduction of outside air into the return. I could write a book on the root cause of noise and never nail the actual cause?????

What he said...

I know...was just trying to be helpful...guessing I'll have to make a trip to check it out, since it's a friend of the wife!

Good idea