My house which was purchased from a bank (foreclosure) was originally wired with both central air and heater (forced air). But when the previous owner left, he took the air conditioning unit. The heating unit (a furnace forced air in the attic) stayed. No modification was made to the wiring as far as I know. Currently the existing thermostat has difficulty with some settings especially cool/fan (ends up blowing hot air) and heating up the house.

I am ready to switch the existing thermostat to Ecobee 3 lite and wonder if there is anything I should change in the thermostat wiring now that the AC unit is no longer connected.

  • Can you post photos of the existing wiring at both ends? – ThreePhaseEel Feb 7 at 12:39
  • So the prior owner removed the condensing unit (compressor unit outside), did he also remove the evaporator unit inside (aka A-coil, refrigerator coils? What I am wondering about is how costly would it be to restore the a/c function. If you circulate air with the blower fan through the ducting, you will be heating the house in summer because ducting in the hot attic will allow heat flow into the air as it passes through them. – Jim Stewart Feb 7 at 12:49
  • The previous owner removed both the condenser and the evaporator units. There is a copper coil hanging outside the house where the evaporator (i magine) used to be. So you are right, the house gets heated in the summer. So far we switch off the thermostat as we have no need for it in the summer time, but I realize that in the winter time when ever we set the the thermostat to “fan or cool” by error, it heats the house instead. – Tony TChibu Feb 8 at 13:36

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