so the final fix was replacing the exhaust fan in the furnace, which
kept shutting down and then the control board would reset. I just wish
the Home App/google next would have given me an earlier warning than it
did. 10 days after the problem started...
WE bypassed the Nest today and the furnace was still sending out errors.
So the problem appears to be in the furnace. The furnace is working but
is sending out faults and the exhaust fan is the suspect at this point.
The Google Home app had indicated...
My furnace is Carrier model 58TN0A090C17-16. I'll have my HVAC person
follow your Nest instructions and send it to you when he does but it
won't be today.
The E74 went away when I replaced the filter in the furnace but then I
got a T04 which tells me nothing. Now I have errors on my furnace. I
have had an HVAC contractor here for 2 visits and neither he or Carrier
can determine the problem and they are...
I may have replied a little to soon. Although the furnace started to
heat after changing the filter, I started getting errors in the furnace.
Eventually I ended up changing the filter again to a lower Merv and now
all is fine.
