Load balancing on HC with Exchange power-shell

Hi all,
 
We had a maintenance on the site 1 on our Exchange server. In HC we use 2 different servers for Exchange. One on site 1 and the other one on site 2.

During the maintenance process on site 1, we saw that the HC console doesn’t respond to the request with the site 2.
 
What we can do when the site 1 is down for automatically balance all the request to the site 2?