We are trying to replace 2 Maple/Chase 6 wire thermostats, one upstairs and one downstairs (one AC unit). We can see where the first four wires go, but there are two wires off to the side (red and black) in the old unit and we can't match them to connections on the new unit. (Honeywell universal). We are replacing them because the ac (upstairs mostly) stays on and cools to 68 or so even if the thermostat is set high or off.

Are you saying that there are 2 tstats controlling one AC unit? What colors are the wires and what are the letters on the terminals that they go to in the original tstats? What model Maple/Chase tstat? Should be able to find the model number inside the cover. Is this a heat pump or AC only? Is the AC duct system also used for heat?

If you have two tstats connected to one unit, most likely somebody rigged it to try and give more control over the system. My guess is that they used the upper tstat one season (heat or cool) and the lower one the other. Unfortunately, unless you know exactly what they had in mind, and do exactly as they intended, you won't have the same results. Very likely not good either. Get back with some more details.

EPM