has a bad odor when the fan is blowing

Chances are you have a heater core leaking. It can be a very small leak but the smell of hot coolant will produce a dead fish smell. Have you had to add coolant lately? Is the carpet wet on the passanger side?

I haven't had to add any coolant and no leaks on the passenger side that I am aware of. However I did flush the system about a week ago because it hadn't been done for a few years and now the odor is almost gone. Do you think this is just temporary? Is there any way to test the heater core theory without tearing apart my dash?

Chances are you got coolant on something and it is slowly going away. As far as the heater core, you will smell it when you run the heater. Also, they will usually leak into the passanger side of the car. THe carpet will get wet with coolant.

If it is going away, it is most likely from the flush you did. Lets see if it stops. However, make sure the coolant is full.

Let me know what you find.

Joe