Hi all,

I've been reading up on the various past posts on "wiring for a Honeywell RTH6300B", but unfortunately none of them seem to answer my exact problem.

I live in a condo which had an old mercury based Honeywell thermostat. We removed it and there were 6 wires: Red, Yellow, Green, White, Blue and Brown (which was not being used).

I purchased a Honeywell RTH6300b, and connected the wires as follows:

Red - R (which is jumpered to RC)
Yellow - Y
Green - G
White - W (which on the RTH6300b also says O/B)

Blue - did not attach
Brown - did not attach.

The result was that the fan turned on, but compressor didn't. I'm thinking that I connected the wires incorrectly. Any help would be much appreciated. It's 100+ degrees here and A/C is sorely missed!

Hi all,

I've been reading up on the various past posts on "wiring for a Honeywell RTH6300B", but unfortunately none of them seem to answer my exact problem.

I live in a condo which had an old mercury based Honeywell thermostat. We removed it and there were 6 wires: Red, Yellow, Green, White, Blue and Brown (which was not being used).

I purchased a Honeywell RTH6300b, and connected the wires as follows:

Red - R (which is jumpered to RC)
Yellow - Y
Green - G
White - W (which on the RTH6300b also says O/B)

Blue - did not attach
Brown - did not attach.

The result was that the fan turned on, but compressor didn't. I'm thinking that I connected the wires incorrectly. Any help would be much appreciated. It's 100+ degrees here and A/C is sorely missed!
I installed a Honeywell myself a few years back and had the same problem. Their printed directions were not user friendly... I called Honeywell and they walked me through it. Works fine. Their 800 number was printed on the installation/instructions sheet. If you don't have the number go to their website.
Jaxmidway

Hi all,

I've been reading up on the various past posts on "wiring for a Honeywell RTH6300B", but unfortunately none of them seem to answer my exact problem.

I live in a condo which had an old mercury based Honeywell thermostat. We removed it and there were 6 wires: Red, Yellow, Green, White, Blue and Brown (which was not being used).

I purchased a Honeywell RTH6300b, and connected the wires as follows:

Red - R (which is jumpered to RC)
Yellow - Y
Green - G
White - W (which on the RTH6300b also says O/B)

Blue - did not attach
Brown - did not attach.

The result was that the fan turned on, but compressor didn't. I'm thinking that I connected the wires incorrectly. Any help would be much appreciated. It's 100+ degrees here and A/C is sorely missed!
Sorry forgot to mention... Make sure your new thermostat is compatible with your existing AC Unit.

Is this a heat pump or gas furnace ? And did you look in the furnace to see what the blue wire is connected to ?

Is this a heat pump or gas furnace ? and did you look in the furnace to see what the blue wire is connected to ?

Hi acetc,

It's a gas furnace. I live in a condo with central air. I don't see where the blue wire is connected to the furance. I'm afraid I'm a novice regarding thermostats AND furnances.

Thanks Jax, for your comments. Honeywell isn't open on Labor day, so I've been trying out various wire combinations. I know, not the wisest thing to do, but my daughter and I are melting away in the 100+ heat in SoCal.

So far, I'm confident that the Green wire should go with G, since the fan does turn on and off. Also based on some Google searches, I'm quite sure that the Red should go with R (which is jumpered to RC).

Here are the various other combinations I used with no luck:

First: White - W, Yellow - Y
Second: Blue - W, White - Y
Third: Blue - W, Yellow - Y

After all that still just the fan turns on but not the compressor.

The blue may be a common wire ,some thermostats don't use a common wire, go to the furnace and look to see what color wires are connected to the two wires going outside, you should also see the blue wire here.