1991 Park avenue No display on Climate control

[Katohio]

I just bought a decent 1991 park avenue and I knew at time of purchase there was no heat or anything there is nothing lighthing up on the display for the climate control tried a new control unit(with buttons that plugs into dash) no luck when I press any of the buttons it just beeps but nothing else can someone please help me thanks.. I need to get it fixed as cheap as possible or my wife will kill me