differtial/heater fan

[Jim Herzig <jimzig@athenet.net>]

I am a little confused reading some of the postings about diff locks.
Owners manual says to lock center only car in is in danger of being stuck.
Lock rear only when car is already stuck.  Postings i have read say center
can be locked under any slippery condition and rear when over 1 inch of
snow.  Is this correct or is it better to leave diffs untouched until stuck.

My center diff is not working properly in that when it is engaged the light
comes on and ABS OFF light comes on, everything is fine.  When i begin to
drive, however, both lights will flicker as i travel over bumps and it
seems as though the diff is locking and unlocking and locking again each
time the lights flicker.  i also hear a clinking under my feet and can feel
the change in the shift lever.  I am keeping out of center diff lock until
i can get it looked at but wanted some ideas if there are any out there.

Also my heater fan stopped working so i tapped the white housing with a
hammmer and it works for a while then stops again until i hit it again.
Any suggestions?  How long will this last if i keep doing it until it dies
completely and is doing this causing more problems.  They are expensive to
get fixed and i just drive the car in winter.

Thanks to all who respond.