I have a gas furnace/with separate AC.
My painters removed an old thermostat without labeling the wires. It was a very old model, probably original to my mobile home (1967).

I bought a new honeywell programmable and am trying to install it.

Colors I have are - black, red, white, and yellow! Help!

You will need to look in the furnace and let us know what wires hook to what terminals in the furnace. Most likely, red to r, white to w, yellow to y, and black to g?