What causes knocking sound from my engine compartment

1993 NISSAN 240SX
15,000 MILES
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QUINNEH
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  • 1 POST
I here knocking sounds coming from my engine compartment when i turn on my fan for my air, and it make the same sounds when i turn my air conditioner on, but much louder. When i turn the fan off it stops. When i turn the air conditioner out it stops.

Please any help will be appreciated greatly.
Jan 10, 2012 at 6:49 PM
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HMAC300
  • ✓ASE Certified Mechanic
  • 48,601 POSTS
  • ASE Certified Mechanic
if you are handy pull the blower motor out and see if there is anything stuck in the heater/ac box. something may be rubbing on the blower motor.
Jan 10, 2012 at 8:09 PM
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