Air Conditioning - Fan works/AC on and off

Hey guys, thanks in advance for any help here. I noticed my thermostat was powered off after about 3 years service (Honeywell thermo, Trane air handler). I popped it off, reseated it, and it came back on. This happened a couple times, but sometimes it woud only blow if I set the fan to "on" from "auto." I figured it was getting wonky, so I bought a new one at home depot (honeywell as well). The new one is battery powered, so the LCD display stays on, and if I set the fan to "on" it'll blow air around my house. But neither the heat nor the A/C will work at all. I did notice two days ago that there was some water on the floor under the air handler. Any ideas on what to try here? I don't have as much electrical experience as I'd like so simplify if you could - till then I'll be Beer 4U2

Did the heat and A/C work before you changed the stat?

Did you turn off power to the system before you changed the stat?

Do you have a meter and know how to use it?

They worked about half the time since this problem started. I turned the power off on the breaker outside the house and switched out the thermostat - the C wire, which was attached on the old one is not used on the new one according to the manual, so I did as it said and taped that off. I can take a picture of the wiring if it would help. I don't have a meter, but that's easily remedied - any particular brand/variety you'd suggest? Thankfully it's cool here this week! Thanks for the help

What are your settings are you setting the installer set up menu to for your system?

Go ahead and post the photos of what you got hooked up.

I've tried a bunch of settings and overrides on the thermostat, but no matter what the compressor out back won't come on and the AC won't work. The fan will blow. Here's an image of the wiring:
http://www.anthonyfransella.com/ac/ACWiring.jpg
I felt behind the filters and it wasn't wet or icy on the walls of the box, although the ground was kinda damp, even a little soggy. You'll notice the blue (C) and orange (O) wires that were used on the previous thermo aren't used on this one. The brown wire was not used on the previous one or this one. Thanks!

If O was hooked up on the Old t-stat, then you have the wrong t-stat.

O is for a heat pump system.. What is the model # of the unit outside?

I guess I do have the wrong one then, got a bumsteer there - The outside unit is a Trane XR-12. So perhaps the old thermo *was* going bad, but I replaced it with an incompatible one...interesting.

I'm not so sure about the T'stat causing the problem here. Hope you saved the original one.

Yeah, I save everything until the end of the projects, often even after just in case. Here's a question: could the original on/off behavior be caused by the overflow safety switch on the front of the air handler in the event of a partial clog?

Thats kinda what I was thinking. Just didnt know what your set up was. I think you probably hit the jackpot there.

The outside unit is a Trane XR-12..

The XR-12 is not a model #.. You need to look at the silver sticker on the side of the unit that shows Model # 2TWR.... ect..

Hey guys, just to finish this off, I was right about the overflow. I replaced the thermostat with a Home Depot brand programmable one anyway to save energy, and cleared the pipes. Worked like a charm. Thanks again everyone! Beer 4U2

Glad to hear anstin3d, now be prepared for something else in the house to screw up, at least thats how it goes at my house. ;) :thumbup: