How can I make the password length less than 6

[vincent mars msa hinet net]

 Sorry, my English is very poor,  so I try to getting it simply.

Our system must be set to 4 digit password and allow users to change their own.
I replaced pam_cracklib to pam_unix, and set the argument min=3 but when users changing their password, they still have to input 6 or more longer.
How could I do ?

We using Fedora Core 1.0