BY STEVE LACKMEYER Business Writer slackmeyer@oklahoman.comA Dallas developer who claims to have secured the contract to buy First National Center visited with tenants Tuesday morning as they battled soaring temps following a shut-off of the landmark building's air conditioning by Veolia Energy. The impending shut-off had been denied by building management for the past two weeks, but was acknowledged Tuesday morning by building manager Jamie McCammon. More tenants were preparing to leave the building Tuesday following the departure of most of the office tenants last week. At Let's Do Greek, owners reported temperatures in the kitchen had hit 100 degrees.Read more on NewsOK.com