rac load balancing

I have a rac with 4 nodes.

When all for instances are up, the load balancing works fine. As proof, I do this in sqlplus

    Connect user/pw_at_service

    Select * from v$instance.

And I see a reasonable randomness for all 4 nodes.  

But when I shutdown the instance on node 1 or 2 and did the same thing I did not see a connection to node 4.

I have not tried node 3 yet.  

Does anyone have an idea what might be going on?  

Thanks

Randy

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