New answers tagged thermostat
Based on the new information... It looks like the blue wire from the secondary side of the transformer is the R, which would make the yellow secondary wire C. I should have read the transformer label, that clearly says BL (Blue) is common, and yellow is 24V.
You should connect the C wire, from whichever unit supplies the R wire. Typically it's the air handler, but since you've given no details it's impossible to say for sure.
If you actually need heat at night and AC during the day, that means that your house's level of insulation is so poor that it's really worth adding some.
The honest answer is no. There are things that will fix your problem, but they will cause more harm at the end. It is like a pill that will only fix the problem, but have no side effects. Your list of wants is long: You want something that is liquid inside the pipe, find the leak inside of the pipe, and then dry inside of the pipe. You are also looking ...
On the schematic, the BL wire in the section labeled "Low Voltage Field Connection" near the bottom of the diagram. That's the C wire. Click for larger view It appears as though the "C" wire is bonded to the chassis, so you should be able to connect the C wire from the thermostat to the chassis as well. In the last photo, if you follow the yellow wire ...
You can either cap the wire with a twist-on wire connector (or similar device), or clip the uninsulated portion of the wire off. Once the uninsulated portion of the wire is covered, you can just tuck it away. To be extra safe, you can disconnect the other end of the wire from the furnace.
It's likely not connected to anything. If you go to the furnace, you'll likely see the cable that goes to the thermostat. You'll also likely see the brown wire either wrapped around the cable, or just not connected to anything.
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