Hi ,

An issue was reported to me where in a new sharepoint environment the users were unable to search anything. Whenever they were trying to search they were getting this message "The search request was unable to connect to the search service in Sharepoint". I looked into the search settings and administration and found that it was fine. The files were also getting indexed and were available in crawl logs. I checked the account used for crawling and found that it was also fine. After some digging I found the solution to this problem. Here are the steps needs to be followed in this case:

1. Open Central Administrator
2. Go To Operations --> Services on server
3. Select the server you are using for query role.
4. Click on "Office Sharepoint Server Search".
5. Check the option "Use this server for serving search queries".
6. Provide credentials and check other settings and click on OK.