Hi Ulrik,

You need to use constructor injection on the ApiController as below

public class YourApiController : UmbracoApiController
{
    private IPublishedContentQuery _contentQuery;

    public YourApiController(IPublishedContentQuery contentQuery)
    {
        _contentQuery = contentQuery;
    }


    public IHttpActionResult Search(string term)
    {
        // Umbraco.ContentQuery.Search(term);
        _contentQuery.Search(term);

        // rest of the code
    } 
}

You can also access this using Current.PublishedContentQuery.Search(term) However where possible using the injected method is preferable.

Hope this helps

Matt