My AC Repairman told me to keep running my Unit until he gets there.....am I supposed to do that?

I just got home from work and noticed that my house is warm. The thermostat is set to 69 but the house temperature says 86. I called my AC reparman and told him that I checked the breaker and the outside unit which seemed to be operating normally. My AC unit has been running all day while I was at work. However, he told me to keep it running until he gets here tomorrow morning. I feel like I am wasting money on alot of warm air being blown through the vents in my home as my electricity is being wasted. Is he telling me to do the right thing?.......I need Help