iMac G3/400 Cooling Fan

My iMac G3/400 slot-loading, (Indigo Blue) runs exceptionally quiet. Does this machine have the same sort of fan setup as in a PC or is there no fan at all? The machine gets somewhat warm, not hot after 2-3 hours, in fact I have occasionally run the machine for 6 hours or more, never gets warmer, but works perfectly, never the slightest hesitation or problem. If there is a fan, is there a way I can check to see if the fan is working? Is there a program in Panther 10.3.9 that will tell me the temperature + the safe temperature of the machine? I am fairly new to Mac so please make your your reply easy to follow. Thanks, Ken.