I have a Honeywell Chronotherm III T8600C. The screws are for O W G R B Y, and the wires are White, Red, Blue, Brown Green and Yellow. Any ideas? WHite, Red, Green and Yellow are obvious. But Brown and Blue? Thanks!!!

I just installed 2 Filtrete 3M22 programmable thermostats in my home, one for upstairs and another for downstairs. The wiring configuration is W, Y, G, and Rh. There is a jump between Rh and Rc. The downstairs unit worked fine after installation. The upstairs unit is the problem. While going through the "testing" phase, the fan worked fine alone and the cooling worked fine as well (I turned down the thermostat to 50 degrees and the unit came on and the fan did shortly after). However, when I checked the heat by turning the thermostat up to 90 degrees, I could hear the unit come on, but the fan never did start. I could turn on the fan manually while in the heat mode. Any ideas?