Control Switch

[ncil]

I have an older furnace, on the side there is a black box that is the limit control switch. There is a silver knob mark Spring and Winter with arrows. I have no idea what this box is for, I do know that when I switched it to the Winter side, the blower ran for what seemed like a long time, almost two hours. Any information on what this switch is or how to use it is apprecited.

[coolguysfl]

On some very old systems there was a consumer switch that allows the home owner to choose a high speed for cooling / air circulation for summer ---- low speed to avoid drafts in the winter.

Your HVAC professional can integrate all the controls & functions to perform from the thermostat.

Do not open the control box - there are no user serviceable components in there. Contact your local professional for additional advice.