overheating of toyota camry 1997 4 cylinder

my wife's car started overheating when she was driving when the temperature control was set to hot and the fan was turned on. it gets back to normal when the fan is turned off.. air is circulating when the fan is turned on but does not get hot, it only gets warm.....She said when it first started happening, she could smell something burning....but then the burning smell is not there anymore.

can somebody please point me in the right direction?? any help is appreciated....

regards

Sam

 

sounds like you should first try to replace your thermostat and if that doesn't help go after the heater core.