Exhaust Blower Running Continually

[chengka]

Good morning,
I have an Armstrong HE80 and over the last few days I noticed the exhaust blower is always running. This has never been an issue before. We are using the AC 8-10 hours a day. The thermostat switch had no effect. Only the main power switch will stop the fan. I am fairly capable, so I could try some simple suggestions. Do I need a service *

[heatseeker]

maybe a safety switch

[Freon]

I looked for information on your furnace (I'm assuming it's a furnace) but found nothing. So here's a shot in the dark.

Turn off the power, set the thermostat to cool only, turn on the power and see if the exhaust fan blows. By exhaust fan I am assuming you mean the draft inducer blower for the heating system. If the motor still is runnning check to be sure the furnace is not trying to light. If the furnace is not trying to light I would suspect the control board at the furnace.

With the power off, mark each wire that connects to the control board from the thermostat. Mark carefully because you'll need that to reconnect everything. Now disconnect them all and turn on the power. If the inducer blower runs then I would be more certain it's a control board issue. Have you had any electrical storms *