I just bought a Honeywell RTH110B to replace a older one that wasn't working quite well as far as shutting off when you wanted it to. Anyway I have 4 wires as follows: Red, White, Blue, and Green. The thermostat has Rh, Rc, W, Y, G. I connected Red to Rh (its jumpered to Rc), White to W, Blue to Y, and Green to G. Everything seems to work fine except the A/C. The furnace in the attic has the blue wire connected to C and not to Y. I tried connecting it to Y just to see if that was maybe the problem and it still did not work so I switched it back. The furnace is a Honeywell S8600C by the way it that helps any. Can anyone solve my problem?

Honeywell does not make a furnace. The number you have is off the spark ignition box see below.

http://customer.honeywell.com/techlit/pdf/PackedLit/69-1954.pdf

Here is your wiring diagram for your new thermostat.

http://customer.honeywell.com/techlit/pdf/69-0000s/69-1799.pdf

Look at 2.3.5 on page 2 of the manual. For the correct wiring.

NOTE try to put the blue back on the y yellow upstairs.

This thermostat has a 5 minute time delay before the compressor will kick on so any of your testing there will be a time delay of 5 minutes.

Read the entire manual all the information you need is in there.


Also you did not state what kind of furnace you have. Electric,gas etc.

You will also have to set J2 jumper for what kind of furnace you have.

Read the manual.

You will also need to set the configuration menu.

Read the manual
Fresh good batterys are also necessary.

Last question. Where were the wires hooked up to the old thermostat?
What was the old thermostats brand and model number?

See number 2 in your manual

Read the manual.

I did read the manual and hooked up the wires accordingly. The furnace is gas. I did notice that the wire coming from the A/C was red and then spliced to make the one downstairs where the thermostat is blue. I have waited the 5 minutes every time and still no A/C. The old thermostat was a Rheem (Round One). On the one one there was 5 places for wires and only 4 used as follows: Red hooked to R, White to W, Green to G, and Blue to Y. The unused spot was B.

Solved it I think. The jumper wire apparently is shorted. I hooked red into the Rc instead of Rh and got A/C to work. Thanks for the help anyway.

The jumper wire is supposed to jump from RC to RH That was in the manual also. Glad you got it going.

From the manual

Note: The red jumper wire between the Rc and Rh terminals must
Be removed in 2- or 5-wire installations. The jumper must be used in
3- or 4-wire installations if you wish to use the mode selector switch
for the fan.