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Where does the fresh air damper connect on the HVAC blower unit (Lennox Model CX34-38A-6F-3)?
I am trying to figure out how to bypass a Honeywell Equipment Interface Module THM5421C to allow me to install a different thermostat. The existing thermostat wires are connected red to 1, green to 2, white to 3 on the left side top there is a wire from a damper going to green to C on the left top and red to VNT 2 on the left bottom and there is a wire from the unit with white to W1 O/B, yellow to Y, green to G on the right top, and then blue to C and red to R. There is a jumper from R to RC and RH on the left top and a wire jumper from RH to VNT 1 on the left top to bottom.
The HVAC guy I just paid a $59 service call to look at wanted $600 to bypass!
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I still need assistance if someone is willing to answer. I can add take pictures if needed.
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Lennox Model CX34-38A-6F-3 is on the outside. I will have to look tonight if there is a different number inside.
Ok. What does the furnace number look like?
It is a G40UH. I found the following wiring diagrams on the Lennox website.
I guess it really isn't a fresh air damper. I found my EIM install manual from the builder and attached a picture of the wiring diagram. It is wired like the top right "Typical hookup of non-powered ventilation". The bottom left shows the wiring for a fresh air damper and that is not what it is. I am really not sure what it is for, I sort of doubt it is for humidity control - we live in the south, very humid, usually trying to get humidity out. There is a humidity reading on the thermostat. If I knew which letter or wire from the furnace or thermostat drive the connection between VNT1 and VNT2 that would be the answer. The other side looks like it connects to "C". The damper and everything is under insulation, only a small brown wire going into the insulation.
I can't really tell if it is closed when not heating or cooling (I would hope it works that way). Why would one need this external source of air into the return air at all? I guess you say most just have a manual damper that is open - doesn't that make the unit less efficient? (FYI - I have a second system that is totally separate for the upstairs that does not have this damper or duct to the outside).
Anyway, yes - please tell me how to connect it properly to the wiring connection on the G40UH.
What if I did one wire to G and one to C?