AC Guys - New Thermostat Issue

[apc10]

My old thermostat is worn out, so I decided to switch to one of the Sensi smart thermostats. My problem is once I have everything hooked up and I adjust the temp for the AC to kick on, it feels like the fan is blowing but I'm not getting cold air. My old thermostat doesn't require the blue wire while the new one does, but it was wrapped around the wire bundle in the wall so it is hooked up. What could be causing this? My AC is 20 years old, so is it possible that it won't work with the newer thermostat? I've gone through the settings on the Sensi a couple times and everything seems to be set up for my system, but I'm far from an AC expert. Below is a picture of the wiring on my old and new thermostats.

[thegrouse]

Your old thermostat was a standard 4 wire hookup. The blue wire you hooked up is probably not hooked up inside the unit. Look at your new thermostat wiring diagram and see if a blue (common) wire is necessary. If it is you will have to find a way to hook it up on the other end. You will need your unit schematic to do this. Be sure you kill all the power and seek help from a professional if you are not comfortable with it.

[apc10]

Your old thermostat was a standard 4 wire hookup. The blue wire you hooked up is probably not hooked up inside the unit. Look at your new thermostat wiring diagram and see if a blue (common) wire is necessary. If it is you will have to find a way to hook it up on the other end. You will need your unit schematic to do this. Be sure you kill all the power and seek help from a professional if you are not comfortable with it.

I opened the panel on the unit in the attic and the blue wire is hooked up. It was wrapped around the wire bundle in the wall so I just had to pull it out and hook it up to the new thermostat.

Here is a picture of that board upstairs. The blue wire is the bottom.

[Chief Big Toe]

following, as i need to do the same

[Chief Big Toe]

I opened the panel on the unit in the attic and the blue wire is hooked up. It was wrapped around the wire bundle in the wall so I just had to pull it out and hook it up to the new thermostat.

Here is a picture of that board upstairs. The blue wire is the bottom.

just looking,,, so the blue is hooked together with the white wire?

[thegrouse]

What does the wiring diagram say on the new thermostat? Sometimes there are DIP switches you need to select for you heating/cooling type.

[apc10]

just looking,,, so the blue is hooked together with the white wire?

My main 5 wires that run from the thermostat are hooked up to C, G, Y, W, and R. There are an additional 2 wires, red and white, that connect to C and Y. I'm not sure where they go, but they do not run to the thermostat.

[apc10]

What does the wiring diagram say on the new thermostat? Sometimes there are DIP switches you need to select for you heating/cooling type.

This Sensi does not have DIP switches. All settings are done through the settings menu on the thermostat.

https://sensi.emerson.com/en-us/support/how-do-i-configure-my-thermostat

[thegrouse]

Do you have gas heat or a heat pump? Your old thermostat had an O terminal being used, if gas heat it may require the W. Check the wiring diagram.

[apc10]

Do you have gas heat or a heat pump? Your old thermostat had an O terminal being used, if gas heat it may require the W. Check the wiring diagram.

Thanks for all the help on this. I have gas heat and pretty sure no heat pump.

Where should the white wire be on my new thermostat? I had a W terminal on the old one, but only a W/E on the new one. I connected it to the O/B terminal because it is across from the W on the old thermostat. Should it be on W/E on the new one instead of O/B?

[thegrouse]

Normally IIRC the W is used on gas/oil heat and the O is for a reversing valve. Did the new thermostat come with a schematic? The schematic will indicate how it needs to be hooked up to function.

[apc10]

Normally IIRC the W is used on gas/oil heat and the O is for a reversing valve. Did the new thermostat come with a schematic? The schematic will indicate how it needs to be hooked up to function.

Sorry, you've asked that a few times and I forgot to respond. No, there is no wiring diagram that came with the thermostat. I've checked all the paperwork in the box again.

I did find this online. I'm thinking the W should go to W/E and not to O/B. Could that be the issue?

[bowhntrmatt]

EDITED:

didnt look closely enough the first time. Yes, you should connect the white wire to W/E for your application

[thegrouse]

Yes, look at your first picture you posted. You will see there are lines indicating "conventional" and "heat pump" It appears the white wire was on the "W" terminal for the "conventional" lines.

[18ncs]

Tagged