I recently moved into a condo and the heater and air conditioner were both working correctly until this weekend. Now the fan never turns off, even if the entire unit is off (air and heater). I've tried turning the fan from "on" to "auto", and it still keeps running. The thermostat is a Maple/Chase and I'm guessing the unit is about 20 - 25 years old. The only switches on the face of the thermostat are a down arrow and an up arrow (to adjust the temperature) a "set" button that, when pushed, shows a series of settings for morning, day, evening and night and displays times and temps (but doesn't say anything about the fan), a switch with 3 settings, "heater", "off" and "cool", and the switch for the fan, which again, only has "auto" and "on" as choices. How do I turn the fan off?? Please help!

The problem might be with the fan and limit control in the furnace or a stuck relay also in the furnace. The thermostat could also be having problems. Try disconnecting the green wire on the furnace low voltage strip or on the thermostat and see if the blower stops.

Thanks for your response. I disconnected the green wire on the thermostat and the fan just keeps blowing. And that tells me what?

Your fan relay or fan/limit control is sticking. You're probably looking at replacement.

MarkwithaK is correct.

Thank you both for your help. Looks like its time to call the electrician!

Wanda

Thank you both for your help. Looks like its time to call the electrician!

Wanda
Negative. Call an HVAC/R professional.

OK, thanks, fortunately for me I contract an HVAC specialist at my work (ambulatory surgery center). But for future reference, why not an electrician? My Dad was an electrician, and he could have fixed this in a heart beat.

It is a different world today than when you Dad did work. Most HVAC units are more complex today and the knowledge necessary to do the repairs correctly is more demanding.