# Exhaust Fan comes on and off randomly when the unit is off.



## SteveWD40 (5 mo ago)

The Exhaust Fan on my neighbors Concord Unit has been coming on randomly and running for hours, sometimes non stop, when the unit is off. The unit works great, no issues other than that. This is the first time I have come across this particular situation. Was just wondering if anyone else has ever seen this problem or similar. Could the limit switch cause the issue?


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## Revolver (5 mo ago)

Forgive me for being unfamiliar with a Concord unit. Could this compare to my experiences with rooftop units that have a makeup air control and damper? Like a Belimo control? What normally triggers the unit to enter exhaust mode?
And what other scenarios (wiring wise) may allow the exhaust phase to begin?
Is all of that control intelligence within the Concord unit or is there a highly capable thermostat or other control somewhere in the building that is capable of pulling the trigger?


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