I can tell you there is only one fan. The 108 and 109 had different fans for the heater and A/C, but the 123 has only one blower motor for both.

I would start with testing the A/C switch. Since nothing takes place when you switch it on I would guess there is no power coming out of it to send to the rest of the system.

Also test to see if you have power coming to the switch. This could be as simple as a blown fuse.