I have an ecobee thermostat that I want to install, but I discovered we have a carrier EIM module in place between our existing thermostat, and our HVAC unit. Here is a wire diagram of the existing setup.

Existing Wiring

Here are the ecobee terminals
Ecobee terminals

The free hanging blue, yellow, and brown wires are part of the bundle of wires in the wall, but are not connected on either end right now. I engaged with ecobee support, but they wanted to check my HVAC control board. I removed the front panel from my air handler and found all the wires, but it wasn't what they were looking for.

Is it possible that I can just bypass the EIM module by splicing the correct wires together..or do I need something more? Thanks for any help.

Inside HVAC

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Wiring diagram on HVAC panel

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1 Answer 1


You can bypass it.

The ecobee will replace all the functions of the EIM.

The Independent Fan function- G

The Cooling function - Y

The Heat Pump function -O/B

If you have two stage cooling/heating connect those accordingly to ecobee.

  • Thanks for confirming, I'll give it a try soon. The only thing - I only have 5 wires coming to the thermostat but an extra W2 terminal that I think is for the Emergency Heat option on my thermostat, which I think activates a heat strip within the air handler? I have never used this mode before and thought it would be fine to ignore it for now. Commented May 21, 2023 at 2:30

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