[DIY dude]

I puchased a programmable T-Stat and there is no wiring diagram. It suggests that I label the wires attached to my existing t-stat connected to Yi/Y2, G, RH, C etc.; however, my existing stat is an older hard wired mercury switch type with no labeling. I have 4 wires coming from the handler - Blue, red, green & white. Can someone shed some light? Its getting hot in here.

[wmproop]

Go to the furnace end of your tstat wires. Trace each colored wire and tell us what its going to,, if you look very close I can`t imagine a thermostat with 4 wires to it not labeled, sometimes the post/lables are hard to see,, also do you have heat only,, or heat and a/c

[KISS]

With only 4 wires coming to the stat, it's easy to identify. Take any two wires and connect together and post a table.

... blue red green white
Blue.
Red.
Green
White.

Post as Excel

Obviously RED-RED shoud not be done and if you did BLUE-RED you don't have to do RED-BLUE.

The three events your looking for are:

1. Only the fan comes on
2. The heater and fan come on
3. The AC comes on.