How much amps does the heater fan draw?

[CdnCory]

My alt. is hooped so I have been keeping an eye on my voltage meter when I come to idle at a red light, and I notice if my fan is on (hot or cold) my voltage drops down instantly. I also have a 2500 w rms stereo, and when I play it at fairly loud volume (with the fan off) the meter barely moves. so how much does this thing draw??

Cory

 

[Billy177]

i am guessing here but i am saying 25 amps. how old is the battery/alt

 

[CdnCory]

Both under a year old, but the alt is hooped, I know that much. At idle I dont think it charges at all.