[cjacquote]

I bought a Honeywell theromstat RTH2300B I forgot to tag the wires, I connected it Green-G,Blue-Y,White-W, Y-R, it didn't cool Then I tried Green-G.Yellow-Y, White-W, Blue-R, still not cooling? How should I connect the wires?

[Stratmando]

You may have to look inside air handle.
If not able to do a quick jump at thermostat wires to verify what controls what, what I commonly see is Red is Red(24 v to thermostat), white for heat, blue and or yellow for cool, and green for blower.
If you connected the red, green and blue and the blower and outside compressor kick in, that eleminates 3 wires, try yellow if blue doesn't work.
Then connect the red, green and white(Hot, blower and heat strip), if that works, then follow the instructions for the new thermostat.
Good Luck

[cjacquote]

There is'nt any a red wire, only green, blue,white and yellow

[mygirlsdad77]

The lack of a red wire means this thing could be wired many different ways in the air handler/furnace. If you can let us know what color wires are hooked to what terminals in the air handler/furnace we should be able to tell you what to hook where at the stat. There is a chance that you blew a low voltage fuse, or burned a transformer in the air handler if you didn't shut the power of to the unit before installing the new stat. Let us know about wires in the unit and we will take it from there.

Good luck.

Lee.