I am trying to install the Noma thermostat thm301M. The manual has 4 wires, R,G,W,Y. In my wall I have the R,G,Blue and Black wires. How do I know which is which? Can you help?

I am trying to install the Noma thermostat thm301M. The manual has 4 wires, R,G,W,Y. In my wall I have the R,G,Blue and Black wires. How do I know which is which? Can you help?

You will not know unless

You marked and identified each wire you removed from the old thermostat just like it told you to in the directions for the new thermostat.

OR

You track down where the wires exactly go on the indoor unit then transpose the colors available to the letters available.

The problem is you have NON standard wiring colors which means you have NON standard wires attached to standard terminal designations. Find out exactly where the color wires are attached to what letter on the terminal strip in the indoor unit and post back.