Thermostat no screen light up

just installed thermostat. I have 4 wires at old stat with red jumper. Installed wyze stat with the C wire adapter. No screen lights up no worky. Spent some time tiring to find info on wiring. Not a lot of support from wyze. Maybe defective, but how do we debug it?
Not happy with a hour of uninstall old, install new, then repeat install old… :frowning:

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You need a C wire on the thermostat side. I think your G (green) wire will become the C wire on the thermostat side if you use the C wire adapter.


Connect Green to the C terminal on the thermostat back plate.

I will try that. Thanks. But what is the sense of including this adapter for people without C wires. I could just run a new 5 th wire top to bottom. I didn’t see anything in video … Or lame instructions to state move a green wire?


Ok, I finally got back to try the C to green wire swap. No worky. No light on thermostat. I have 29.8 volts at Y and R terminals. Maybe I should just run a 5 lead wire and connect C at thermostat. I wish Wyze would just state what wires are needed at plate. Power schematic would be nice. I may just have to return this unit and go with a Nest.
Does anyone one know if we can run 5 wires and eliminate the need to mess with the C wire adapter?

Stick with the Wyze thermostat. Let’s see if we can break this down and not even use the adapter as I was in the same boat.

  1. In one of your pics, it appears the circuit board that is on your furnace has 5 wires coming off of it. Red, Yellow, Green, White, and Blue. Obviously, the cable colors don’t match with the circuit board color labels

  2. If all 5 of those cables listed in step 1 above are fed to the back of the thermostat, then simply coordinate the appropriate colors.

  • 2)a. In your original thermostat pic, I see 5 cables. Two that are red which correspond to the 2 red on the original thermostat. One is obviously for the “red” slot. The other “red” cable is most likely coming from the “C” slot on the furnace which would help complete the circuit.

  • 2)b. That extra “red” cable going to the old thermostat, can you remove that and plug it into the “C” terminal?

You moved Red wire from Rc to Rh
Move it back to Rc. Wyze does not use Rh.

If U can run extra wire for C …I would do that tgan using adaptor

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Thank you, I moved red wire back to RC not sure how I missed that in second install. Did the firmware upgrade. Good. It seems to be working except, the fan (blower) starts immediately when the thermostat calls for heat. The old thermostat waited till the flames (heat) started then kicked the blower on. Is this a setting with-in the software? Or will we have to live with it? I probably should post a new thread.

I believe Wyze need to put a hazard statement in for people installing in the (north) winter time. We can NOT test AC function without possible damaging the outside compressor. Hopefully it will function fine for our AC this summer.

Blower starts is a bug. there is another thread reported. You should sent in a service report so the firmware can be reviewed by Wyze.

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This is due to the C-Wire Adapter. Normally when there is a call for heat, the inducer motor turn on to close the pressure switch, which then opens the gas valve. The IFC has a built in timer to delay the blower while the heat exchanger warms up. The C-Wire Adapter seems to bypass this by applying 24v to G directly activating the blower. Your only real work around is having a new 18/8 or 18/20 Hybrid wire pulled from the furnace to the thermostat and do away with the adapter.

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I like the idea of eliminating the adapter. Keep it simple. I will run the new (18/8) wire, but what should the connections look like. Should I just go wire for wire on color? Where do I need the voltage? :slightly_smiling_face: I don’t want to mess up what is working now. Thanks.

Red to R, White to W, Yellow to Y, Green to G, Blue to C

No change in blower start up by eliminating the C-adapter. Got new wire installed. ran 5 wires one as C. The blower will start when stat calls for heat. I guess it really is a bug in the software. I took pictures of new wire hookup. FYI: The 2 lower wires (yW & oR) at the board are connected to a humidifier.

The cabling looks good.

  1. Have you updated the software on the thermostat?

  2. Have you uninstalled and reinstalled the app on your phone? ( I hear for some odd reason that helps)

  3. Do you have a dual zone environment?

This is a defect in the wyze’s programming. Most thermostats do not send a signal for fan when heat is called on a gas furnace, because the furnace takes care of the fan timing. For some reason, the wyze asks for fan even when you have selected gas as your heat source, and thus it starts the fan right away, before the heat exchanger has a chance to heat up. Hopefully wyze fixes it soon.

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I have disconnected my G wire to the Wyze thermostat to fix the fan turning on immediately. Before that it used to spin up immediately and stop after a few seconds, and then start running a normal cycle after a while.

Within “Advanced Settings”, what is the Fan Cycle set to? That is the minimum amount of time the fan will run per hour.

So if you change (advanced setting) minimum fan time to zero. Will that be same as disconnect G wire?

No or not to my knowledge. That setting just simply defines the minimum amount of time per hour that the fan will cycle air. The default I believe is 5 minutes. I was more of curious to see what the person that is having issues had their set to.

When in doubt, people have resolved issues by reinstalling the Wyze app.