thermostat wiring-- Where does the blue wire go? its HOT out!

rutterback · Jul 28, 2009, 07:27 PM

i bought a Honeywell rth221b thermostat. I was smart enough NOT to mark the wires when i took off the old one.

the wires that come out of the wall are red, green, white, and blue. The thermostat looks like this-

Y-o o-Rh
G-o o-Rc
o-W

Im assuming green to G, red to Rh (Rh and Rc have a jumper between) and white to W. Where in the world does blue go??? my heat worked but not my central air. Im assuming the A/C is the blue wire?

Like a typical guy, i threw away the instructions months ago and never checked to see if the AC worked.... Smart... I know.

Thank you in advance for your help and tips.

ballengerb1 · Jul 29, 2009, 07:20 PM

move the red off the yellow leaving the blue still connected to yellow. Move red to the empty G on the right.

siberianair · Jul 30, 2009, 03:55 AM

check the fuse near your curcuit board or maybe you blew the transformer.
you did turn the power off before playing with wires on tstat didnt you?

rutterback · Aug 12, 2009, 12:58 PM

nothing is working!! please help!!! its 95 outside!!

rutterback · Aug 12, 2009, 01:04 PM

I never shut the power off like an idiot. i dont know if there is a voltmeter either? im going to try what KISS said... ill report back.. thank you

ballengerb1 · Aug 12, 2009, 01:40 PM

I never did understand siberairs comment and reddie to me. He said I was wrong but never explained further. I have not seen a board on the furnace with 2 wires going to it. The blue/yellow sends the signal, the second red should be jumpered at the stat.

ballengerb1 · Aug 13, 2009, 05:09 PM

This may amuse you but I see that Siberianair has been blocked out as a troll. Maybe skip his suggestions for now.



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