[nsp] Cisco 1750 fan operation?

[Ed Ravin]

On Thu, Jun 24, 2004 at 01:30:10PM -0400, Ed Ravin wrote:
> While doing a little surgery to upgrade memory on my Cisco 1750, I
> noticed that it has a little 5VDC 1.5" fan in the top cover.  But the
> fan doesn't spin when I power up the box,  Also, my VOM couldn't see
> any voltage on the fan's motherboard connector.  Is this normal for the
> unit, i.e. does it only activate the fan when needed, or is something
> wrong?

Nothing is wrong, except that I forgot to Google before posting that
message:

   http://www.cisco.com/en/US/products/hw/routers/ps221/products_field_notice09186a0080094488.shtml

   [...]
   Problem Description
   
   Fans in the Cisco 1720, 1750, and 1751 routers are not running when the
   ambient temperature is below 45°C (115°F) measured on the outside of
   the router case.
   
   Background
   
   The fans are designed to only run if the ambient temperature reaches
   45°C or 115°F (+/- 8°C) measured on the outside of the router
   case.
   
   Problem Symptoms
   
   The fan is not constantly rotating when the unit is powered up. This can be
   incorrectly interpreted as a defective fan.