Hello everyone. I have an older M1M on the board in the furnace it only has four connectors and connections:
C (Blue wire)
W (White wire)
G (Green wire)
R (Red wire)
The older thermostat had the following connections:
R (Red wire)
W (White wire)
Y (Blue wire)
G (Green wire)
I tried one for one when installing the Honeywell T9 matching what was connected at the furnace circuit board:
C (Blue wire)
W (White wire)
G (Green wire)
R (Red wire)
With this setup I'm able to engage the heating, and fan. I'm unable to get the A/C unit to engage. I have the C wire adapter, but do not see a location on the circuit board to connect the Y wire. Any assistance is greatly appreciated in helping me get this sorted out.
Thank you in advance,
Chris
It sounds like you used the blue Y wire for C now. You will likely have to buy the Honeywell Power Adapter. This will allow you to use a 5 wire system with only 4 wires. Didn't the T9 come with the adapter?
If not you can buy one here,
https://www.amazon.ca/Honeywell-CWIREADPTR4001-C-Wire-Power-Adapter/dp/B07VMV2BJ7/ref=asc_df_B07VMV2BJ7/?tag=googleshopc0c-20&linkCode=df0&hvadid=360115781192&hvpos=&hvnetw=g&hvrand=1318869463037421328&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1002304&hvtargid=pla-861786070484&psc=1
It came with the adapter. I'm unsure how to wire it in since the circuit board only has the 4 ports listed. I did not see a "Y" on the diagram. Is it possible to use the blue wire for Y, and C? On the old thermostat it was connected to Y, and to C on the control unit within the furnace housing. Is it possible to splice the adapter "C" wire to a different 24v source on the circuit board, and place the other wires accordingly?