No Y connection on control board. Help!

Please help. There is no connection for y on the control board. Just c. There is a y connection on the thermostat. But no c. I’ve included some pictures one of which is the diagram.
I guess I can only include one pic as a “new” user. Picture is the control board connection. I’ll post the diagram and thermostat in comments.

the Y wire at the tstat most likely is going straight to the AC unit, along with C from the control board. It would probably be helpful to post a wider shot at the control board showing all wiring.

Have you checked behind the tstat for any extra wires that arent being used, maybe wrapped around the cable? If there is none, you’ll need to install the C wire adapter, but I’m unsure on the wiring w/o Y. @speadie will know.

The main board picture may not be the connection to the thermostat. Check for wire bundle with knobs from there. More pics.

I think cf7 is on the right track. Look for where the thermostat wire enters the furnace, Just because it doesn’t go to the furnace board doesn’t mean that the wire isn’t in the furnace. The schematic shows the Y wire going through a wire connector block somewhere.

Thanks all. Here are more pics.
The first three pics are where the wires come from the thermostat. The c and y wrap together in that cap. I included a couple of where they go from there and tried to get a better view of the area with the control board but space is cramped.

Your wire bundle next to furnace power switch shows where the Y (A/C) wire is. If trace down it goes to another board.

You can use Wyze adaptor without pulling additional wirefrom furnace to Tstat.

But if it is easy to pull additional wire. You just tap that wire to C and you are set.

This looks like a package unit - outdoor unit, all in one with the compressor, coils, and furnace/ air handler contained in one enclosure.
The yellow wire in this wire nut on that contacter should be the Y wire.
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The blue wire on the other side of the contacter coil will be the common or C wire. Make sure the power is off when working inside this unit, The high voltage terminals are exposed and would be easy to accidentally brush your hand against.

The easiest way to hook up the C adapter would be to cut the blue wire inside the furnace and splice in another length of wire to it and run that wire to the outside of the unit where the other wire nuts are.
Whatever color that new wire is, it should be labeled C, and connected to the C wire on the C adapter. Then you would attach the yellow Y wire from the furnace to the Y wire on the C adapter, and the blue Y wire from the thermostat to the terminal strip on the C adapter. The Red wire coming from the furnace would be connected to the R wire on the C adapter, and the Red wire from the thermostat would be connected to the R terminal. The White wire coming from the furnace should be connected to the W wire on the C adapter, and the white wire from the thermostat should be connected to the W terminal on the C adapter. Lastly, the Green wire from the furnace should be connected to the G wire on the C adapter, and the green thermostat wire should be connected to the G on the terminal strip.
Then you would connect the green wire at the thermostat end of the wire to the C terminal on the wyze.

Hey guys!

Thanks so much for your time and effort in this. I truly appreciate it. Forgive me I have no experience with any of this. Does this look right? I’m just making sure where I took the y wire from will work correctly and I attached the c wire from the adapter to the same connection as the blue c wire that was already attached.

I don’t know if this could cause any safety issues in the apartment so I wanted your opinions first.

It looks correct from what I can see from this angle. I’m assuming the yellow wire that comes up from the contacter’s 24V side terminal goes over and then down out of sight and then goes to that wire nut.

Is there anyway I could have reversed the air flow? It is functional and I can control heating and cooling from the wyze thermostat, but there was a strong burning smell and the air for both cooling and heating was blowing outside from the tube in the picture.

The tube is probably the exhaust from the gas burner. Do you mean that the gas burner is running in A/C mode?

You might be putting too much power through the R wire in the C adapter, because all the power for the heating side has to flow through it from the A/C side. This is one of the reasons I suggested that you put the C adapter where the thermostat wires come directly into the unit. I’m not sure how much power the C adapter is rated to pass.

ohhhh, okay. I think I understand now. So I won’t have the the c adapter connected to the control board? I am able to just connect the wires where the wire nuts are? I’ll run a lengthy piece of wire up there from the C wire? It appears the C wire is plugged into V2 GND and goes through the transformer and contactor before plugging into the control board. Where would be the best place to splice a wire into it to connect to the c wire on the c-adapter? Or does it matter?


Right. If you look at the schematic that you posted, you can see that the “control board” that you have connected to is just for the blower fan. there is a second control board for the furnace ignition side of things, but there is no central control board. You really want to be upstream of the interconnects that happen inside of the furnace with the C adapter, as close to the actual thermostat wires as possible.

It would be ideal to splice into the Blue C wire from where it comes out of the connector block and runs over to the ignition control, so that you’re not running current through other devices in order to feed the thermostat’s power draw. Using the schematic, you can see that that wire has a direct feed to the transformer, without going through other devices on the way.
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Right now, with the way you have it hooked up, all the power for the ignition control board and gas valve, and anything else in the furnace side of the unit needs to go through the C adapter, which may not be rated for that much current.

Would you suggest adding a in line fuse to C if connect close to transformer.

Yes. It is somewhat surprising that there is no fuse directly after the transformer.

It seems hooked up correctly. It turns on but the same issue exists where I don’t think the blower is functioning as no air is coming out of the vents for heating or cooling. Any idea?

Adaptor blue wire is not connected?

Post pic of Wyze Tstat wiring.( Current.)

What is setup in app?