Hello everyone, It's getting colder in my house every minute
I have Carrier 58TUA furnace
It work great until yesterday when I've noticed that it never turns
off for some reason
I got new thermostat first but quick fix failed
I can only turn it off using switch on the furnace
LED error code is 12
BLOWER ON AFTER POWER UP (115 VAC or 24 VAC) -Blower runs for the
selected blower off-delay time, if unit is powered up during a call
for heat (R-W/W1 closed) or (R-W/W1) opens during blower on-delay
Is that control board went bad?
It is the cycle that the heater goes through when the power is returned AND
the wall thermostat is calling for heat. [90 sec. blower run time.]
If the blower won't quit running after you plugged in the heater, and you
are sure the wall thermostat [fan] switch setting is to AUTO, then it is
likely you have a situation that requires a qualified CARRIER service tech
see why it's doing what it's doing. I know what the problem is, and it
[honestly] should be checked out. You [might] have either a firebox
failure, flame roll out condition, or a conditioned air mixing with
combustion air problem. All of these are dangerous and should not be
addressed by a DIY. Call a licensed HVAC company and have them check your
Maybe I stated the problem wrong
I have thermostat turned off yet furnace starts to run heats the
It just never stops
LED does go red after 90 sec
another thing that troubles me is that if board is bad
can I trust the error code that I'm reading from the board?
Nope. Never trust the error code. Get a new board. You might need a
new gas valve and igniter too. After that, replace the thermostat and
match it with braided thermally shielded blue conductor thermostat
wiring type FE-8.
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