Heater Cores or Heater Fan....HELP

When i turn my heater on it make a strange noise (very loud actually) as something is either stuck in the fan or the fan is coming off...then the noise will sometime go away or come back in periodically. When I cut the heater off. the noise of course goes away. When the heater is on, it want matter if the heat is turned up high or low the loud noise still begins. Just wondering, what can be the problem? Is it the fan gone bad or the heater cores... Is this something I can easily get to and change or would it require a mechanic?

usually this is the fan (blower motor) getting bad, usually due to a condensation problem also. Eventually you will start losing fan speeds due to the increasing resistance of the fan overheating the control resistors also.

#1. Fix the condensation problem (if you have one)
#2. Replace blower motor (search this forum for the info since it is a common problem/replacement)

Typical Intrigue problem.