Did I mess something up?

[u/Grimm0020]

I set up our Nest Gen 3 yesterday and the AC worked fine for hours no issues. Today the system now loses power, makes clicking noises before it turns on again and repeats. I was messing around with settings and put it in heat and cool mode before going to bed last night which didn't work as intended. Then we had to turn off eco mode today cuz it wasn't turning on manually either.

Looking back at my work it looks like I put the Heat wire in the wrong place but it didn't give me issues yesterday. I wasn't sure about it due to the labeling in the old thermostat. After doing some research, it seems like the Nest just isn't getting enough power anymore. I noticed we also have a blue wire that wasn't used with the old thermostat that is still tucked in the wall and it seems to be a C-Wire. I looked at the furnace circuit board and I do see a blue and white wire connected to C.

I wanted to see if anyone might know what the problem might be before I try anything and plug in wires that weren't being used with the old thermostat.

[u/sryan2k1]

Hook C up at the furnace using that spare blue wire, and hook it to C on the thermostat. You may also have a condensate/overflow issue. But the clicking likely means the thermostat is low on power.

For now pull the display off and charge it with the USB port for a few hours.

Show pictures of the furnace end and we can help make sure you get the C hooked up correctly.

[u/Grimm0020 → u/sryan2k1]

Yeah this is what I was going to do. The blue wire is already connected to C but there is also a white wire connected to it. I'll post some pictures of our furnace as soon as I get home. I posted this very early in the morning cuz I was stressing out over it thinking I messed up somehow. Thank you.

[u/sryan2k1 → u/Grimm0020]

On a conventional furnace+AC there will be the wires coming from the thermostat, and then another 2 wire cable that also connect to C and Y. Normally Y will have 2 connections (the one from the thermostat and the one out to the outdoor unit) and C will only have one (the outdoor unit). If the thermostat bundle has enough wires for C it will also get landed on the C terminal.

If the blue going to the tstat bundle is already hooked up all you need to do is turn power off, strip it at the thermostat, insert it, and turn power back on.

[u/Grimm0020 → u/sryan2k1]

Connecting the C-Wire worked! Looks like it was just a power issue T_T So far the AC isn't shutting off within a minute and no more clicking sounds as it tries to turn itself back on. Thank you!

[u/FIRElif3]

I think this is where everybody says go check your blower units float it’s probably sitting in a pool of water

[u/Grimm0020 → u/FIRElif3]

Oh I see :( I don't know much about this stuff but I'm learning as I go. Our home warranty might cover it just in case I'm not sure of things and let a professional take over. Other than that, was the wiring done correctly at least? No need to mess with anything on that end?

[u/ebusch73 → u/Grimm0020]

If you're getting an error like e74 "no power to Rh" then that could indicate a clogged drain line which is tripping the float switch. This would be easy to verify by looking to see if water is backed up into the drain pan beneath the air handler.

If it's just low power that's not keeping the Nest charged, then hooking up the C wire should fix it. Actually either way you should hook up the C wire since it's already there.

[u/FIRElif3 → u/Grimm0020]

Wiring looks fine

[u/Grimm0020]

Thank you guys for the response! I wont be able to work on this until alter today so Ill update later and try the suggestions.

[u/Grimm0020]

Issue fixed 🙏🫡 C-Wire solved the problem!

[u/ebusch73]

Since you have a spare blue wire in the wall, which already seems to be connected at the furnace end, plug that into the Nest's C terminal. That should help to keep the Nest fully charged.

The white wire into W1 for heating is correct. Your old thermostat has alternate labels for a heat pump (the O and B terminals) and in that case the white wire would have gone into W2/Aux. You appear to have a conventional A/C so W1 is the correct terminal for your system.

[u/ebusch73 → u/[deleted]]

I'm well aware that they don't have a heat pump. If they did, either the O or B terminals would be used, but they weren't.

[u/ebusch73 → u/[deleted]]

Again I'm fully aware. The OP mentioned they thought they messed up their white heating wire. Presumably they saw the original "W/Aux" label and put it into the "W2/Aux" terminal on the Nest. That would have been correct had they had a heat pump with aux electric heat, but with a conventual A/C and electric furnace it should go into W1.

In this case the "Alternate Label" is W for conventional and Aux for Heat Pump.

[u/funkystay]

Move Rh to Rc.

[u/sryan2k1 → u/funkystay]

All nest thermostats with multiple R terminals internally bridge them when only one is connected, it does not matter which one you use when there is only one R wire unless you are also using a nest power connector.

It is HVAC convention to always use "Rh" when only one R wire exists and both terminals are there.