Does this old furnace have to go.

The furnace is 35 years old and needs a circuit board that’s no longer made. The replacement board requires extra parts to make it compatible, with repairs estimated at over $500. On the plus side, the heat exchanger is still in good shape. On the downside, the draft motor and blower motor are also 35 years old. Aaac Service Heating and Air recommended replacing it, but since we’re not a high-pressure sales business, we provided a repair quote as well. The furnace was repaired, and hopefully it will serve them well for a long time, though the old parts aren’t covered in any way. 

These pictures are not of same unit. It's all I had. 

What does this link button do.