When i am trying to open Central Admin in SharePoint 2013, I got this issue http error 503. the service is unavailable.
Resolving this issue, Go to Start->IIS->Click on Applicati on Pools->Select SharePoint Central Administration v4->Left side select advanced settings->Click on Identity
Click on Set Enter Credentials with Username and Password Click Ok.
After completing the Steps Reset the IIS
Refresh the Page now we can able to open the Central Admin.