Why did my air conditioner quit & fuel management display go dark? on 1991 Cadillac DeVille

The fuel data center and air conditioning went out at the same time. I was told by Cadillac mechanic that I need to replace the Fuel Management Display #1228851 and climate control display #19151967. I Cannot find these part numbers and neither could the dealership mechanic. Any suggestions?

Asked by for the 1991 Cadillac DeVille