AC condenser/blower problem: Blower will not turn on.

I have a combined gas heat/AC unit inside and an exterior Compressor for AC. It is an older Carrier unit ( 58Gs100-3) and about 20+ years old. Both the cooling and heating worked last summer and this winter respectively.
I'm trying to use the AC now, but the only thing that comes on when the thermostat calls for AC is the outside compressor; I can't even get the fan to go on when I put the thermostat on a "FAN ON " mode. I even tried using a spare thermostat, but there was no change.
I changed the thermostat recently and I'm thinking perhaps something on the circuit board has blown ( 302075-304).

Any ideas?

I direct-connected the HI wire to the blower to the black AC wire and the fan stayed on. So yesterday I was able to cool my house with "forced" air ( sorry, bad pun!)
Today I installed a new controller, and everything looked good, but the problem is still there: Compressor kicks in when the thermostat calls for AC, but the blower does not go on... even with the new controller!! Heat still works and blower goes on when heat is called for.

What could the problem be?