I joined a co-worker (who is currently doing something) to this site - so after this post there will be no more "him"ses vs "I" 's for the pronouns. :) (and I'm sure he loves the "username" I chose for him)

The problem he is having is that he has 5 wires from the wall that used to be hooked to an old Hunter NON-programmable thermostat (model unknown), and is hooking it to a newish Hunter 4415c programmable therm.
The unit (a/c/heat) is electric.

The wires from the wall are R, G, Blue, Y, & W.
The wires /positions on the 44155c are:
RH - 24v
RC - 24 volt cool
G - Fan
Y/O - A/C compressor
W/B - heating or reverse valve operation in heat mode.
Y1 - heat pump compressor (which he doesn't have).

He says he hooks the white to Y/O to get heat and unhooks it to get A/C.
The R he has hooked to RH/RC (jumpered), and Blue to W/B
Unfortunately he doesn't remember what he has hooked the Y & G wires to, I'm sure he will add that later when he gets the time to log in.

Any help with this problem will be greatly appreciated...

(yes I am a "polite" smarta**) :)

You should have a choice of electric, conventional or heat pump. Pick electric for the tstat setup.

Which means Rc/Rh to red
G to green
White to W/B
And yellow to Y/O

Blue is probably common and needs to be capped or connected to the C terminal.