If it's in the back of the unit it's probably the power supply fan. And yes, it's supposed to run all the time. You should have other fans also and they all need to run.
Question. Would you run your car with no radiator? Same scenario, same end results. Fans are cheaper than a new PC. Pull it out and take it to a computer store for a replacement.
Motherboard Monitor is a great program and free. Do a Google search. It will support most mother boards.
XP Pro 2002
CPU 2.53 GHz
Have tower with window so that I can see into the system. Just by chance I noticed the fan in the upper back part of tower has ceased turning. Opened tower and manually started fan. Turned on my PC and fan worked for about a minute and then has stopped again.
Is this fan supposed to turn ALL the time? And is there a program that will tell when your system is heating up? I fancy I smell units heating up but not sure if it is real or my imagination since I do not see that fan working now.