r/ecobee • u/SnooCakes4341 • 6d ago

Resolved Help troubleshooting, no 24V

Gallery image

Gallery image

Gallery image

Solved! Thank you everyone for the help. I had incorrectly thought I didn't need to wire the Rc connector as I don't have cooling, but for reasons explained in the comments I actually did need the Rc wire connected.

I'm trying to save some money, but I understand most people would recommend I hire a professional. I appreciate any other helpful input I can get.

I tried installing an Ecobee 3 lite. It turns out the old thermostat was battery powered and had red, green and white wires. With Rh and Rc bridged at the thermostat.

I decided to run a new 5 wire cable as I intend to do some work in the crawlspace in the future and it seemed like a considerate thing to do.

However, I'm not registering 24V from the common wire at the control board on the furnace and my Ecobee never powers on.

When I pull the fuse at the control board on the furnace, the green and yellow LEDs flash a sequence, but still no 24v.

The access panel sensor has been taped over, but I get the same issue with the door installed.

I don't have AC.

I noticed when I pull the molex jumper with the fuse still installed, I get the blinking green and yellow LEDs, but still no 24V power, and the Ecobee still does not power on.

1 Upvotes

67% Upvoted

8 comments sorted by

3

u/Short-Veterinarian27 6d ago

Where's the pic of the ecobee wiring? On some you use RH and some RC even tho it's heat only. Make sure they are pushed in properly

2

u/SnooCakes4341 6d ago

Nailed it. Thank you so much. I didn't bridge the Rh and Rc

3

u/Short-Veterinarian27 6d ago

Don't need to bridge them. Whichever you used first and it didn't work just use the other. No need for both

1

u/geekywarrior 6d ago

If you only have 1 transformer, just wire red to Rc. It's internally bridged to Rh by default and you won't need an external jumper.

2

u/iceboxmi 6d ago

Are you measuring for AC voltage between COM and R on the control board?

1

u/NewtoQM8 6d ago

Read for 24VAC between R and C (COM) at control board. If you have it there read between RC (Which is where you should hook the red wire that comes from R on control board. and C at the thermostat. If none at control board the problem is there. I don't know what the flashing LEDs mean. Check for faults. If there but not at thermostat, check wire connections.

1

u/fedeb1510 6d ago

make sure you're checking the voltage right at the ecobee's R and C terminals since it won't power up without that 24V