Air conditioner will not shut off

Old 08-14-15, 10:47 AM
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Air conditioner will not shut off

I installed a new thermostat (ecobee3) recently and thought all went well. I was replacing an old Honeywell without a C wire. Luckily the C wire was in the bundle, it just wasn't hooked up. So I connected it to the thermostat and then to the 'com' connection on the blower control panel.

Everything worked until I woke up the next morning and noticed the AC was still running (fan and compressor). The pipes were frozen and there was condensation on the furnace, so I ran the blower fan for awhile and shut off the AC at the breaker.

I've checked the contactor, which seems fine, nothing seems stuck there. And I've pulled the thermostat off the wall, and the AC will still start up immediately when I flip the breaker.

So for some reason the contactor is getting a constant 24v. There are two wires going from the AC to the blower. A white, going to 'com' and a red going to 'R'. That seems right to me, so I'm not sure what else could be wrong? Any ideas? Thanks!
Old 08-14-15, 05:42 PM
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The red wire from the condenser should be moved to the Y terminal at the furnace (along with the stat Y wire).

If the furnace does not have a Y terminal connect condenser red to thermostat Y.

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