My 1990 300CE puts out both cold and hot air at the same time. The hot air comes from the left and right side vents and on the left side of the center vent. Cold air comes out of the center vent in the middle. What could be causing this?

Someone told me that the board behind the AC controls is at fault.
If so, can reconditioned boards be bought?

Any help on this subject would be greatly appreciated!

go.dale@verizon.net