Thermostat line connection?

[Tong]

Hi

My thermostat is broken. Jut took down my old thermostat and found that blue line is connected with yellow line together.

Is this normal? When new thermostat arrives, should I connect blue line to B?

Thanks in advance.

 

[WorthFlorida]

Not sure why. Maybe someone didn't know what to do with it. Most Smart and all WiFi thermostats (no batteries) needed, the C wire must be used. It's the common wire for the return side of the 24vac so the electronics and screen will have power all the time. You'll need to look at the HVAC side to see where the Yellow and Blue wires terminate to. The control board in the unit will have the same labels. If you bought a standard programmable thermostat that requires batteries, the current wiring will still work, even with the blue wire on the yellow.

 

[Sponsor]

 

[Tong]

My new thermostat comes. Following the color coding........and...... it does not work!
Then, copy the old ways, i.e., put blue and yellow line together.
It works! Very strange configuration.

Still have some problems.....journey continues.

 

[WorthFlorida]

The yellow wire may opened somewhere. You really need to look at the other end.

 

[Fitter30]

Hard to tell if theres more than one thermostat cable by the pic. Normally stat cables run to furnace then to condenser. If blue is one cable and yellow the other possibly made the connect at stat not at the furnace.

 

[Jadnashua]

The only way to tell for sure, would be to look at the other end of the cable and see what is connected to what. While it would seem logical, not everyone wires things up 'by the book'.