Ok until about a week ago everything works great on my car... Its a single fan and i use the old turn the ac "on" so the fan turns on. (move the switch so that the ac is "on" even though its not, my ac is all gone... basically a switch for the fan. ok so now when i turn on my fan when i'm driving the tach jumps to 0 and the car runs erractically for about 5 secs.... (almost stalling) and if i turn the switch back off while it does that its fine, the problem stops instantly.... if i start the car with the fan on already the car won't rev up right, it runs like crap up top... the car is fine without the fan on. as soon as the fan is turned on it runs like crap. it only started this about a week ago... i have a new alternator and battery installed.... (Like a month ago new) any ideas? Thanks

 

and now it does it when i have my heater fan on full, anyone have any ideas?

 

Do you still have the compressor? If so, maybe its dragging when you try to turn it on. If you have it try unplugging it.

 

Compressor is gone.... i was told a bad ground somewhere...

 

Check for a short in the A/C wiring and check those fusible links at the starter.