Replacing old Airtemp Thermostat with a Programmable one

[Poz]

I have a 1974 Chrysler Airtemp Packaged roof mounted HVAC unit.  The Airtemp thermostat has 5 wires going to terminals labeled R,Y,W,G and A.  The Lux Programmable thermostat does not have wiring diagram that matches my old thermostat.   I called their tech support and they suggested that I connect all but the A terminal wire and try it.  It did not work!  The unit would work in heat mode but the fan would not work on Auto, so it never came on.  I could put the fan switch to ON and the unit produced hot air if the thermostat setting was above room temp for heat.  I did not try A/C mode.  I can get the schematic from inside the enclosure on the roof and probably the model number of the HVAC unit.  There is no part number on the Airtemp thermostat.  Anyone have any useful suggestions on the 5 wire Airtemp thermostat replacement?

[jumptrout51]

What color is the "A" wire?