Something you really need to understand.

The colors of the wires that attach to the thermostat mean absolutely nothing. Some installers might connect colors of wires that start with the same letter as the terminals, such as yellow for Y, green for G; but that is totally arbitrary. Thermostat wire manufacturers don't make the wires certain colors for the choice of letters that are on a thermostat, the certainly don't make wire colors like Rhesus color for Rh terminals and other strange names for colors. What would go on a B terminal? - Black? Blue? Brown? Wire colors are just a convenience to be able to find the other end where the furnace or air conditioning machine is located.

First thoughts of an experienced AC repairman:

1. What make and model thermostat is it? There are NO thermostats that are exactly like others made by other manufacturers, that's why instructions come in the box with thermostats.
2. Was it a thermostat recommended by the manufacturer to be used with the particular brand and model of the AC; or was it a guess by SOMEONE, pro or amateur, that it would work. Is this a thermostat recommended by a Big Depot clerk making $7.50 an hour? He's working there because he doesn't like to make the union HVAC wage of $27 an hour?
3. Were the wires installed by a pro, or was this whole project an experiment by an amateur DIY, so how long will this take to test the wiring?
4. Heard this before; who installed it - original install, new by a pro, DIY project - all different results.
5. What do the instructions say about setting it? What are all the features? Is there a setting like time-of-day programming that are confusing the temperatures?

These are the questions you are getting into and more.