21 - EN
A7
pre heater
does not heat
sufficiently.
Release the front panel
by unscrewing the screws.
Remove the plastic panel
in front of the control circuit board
Is the
resistance of
the pre heater
element > 100
?
Yes
No
Disconnect the power from the
ComfoAir.
Lift the front panel from its hinges.
Yes
No
Resistance of
the NTC sensor
T1 correct?
Replace the
control
circuit board.
Replace the
NTC sensor.
Yes
No
Is the
resistance of
the pre heater cable
infinite ?
Replace
Pre heater
cable
Yes
No
Are the
connections
at
the pre heater
correct?
Replace
Pre heater.
Reconnect the
pre heater.
Install all parts in
reverse order.
Reconnect the
power to the
ComfoAir.
Is
P51 and
P57 set to
the correct
value?
Yes
No
Set P51 and P57 to
the correct value.
Reset the malfunction
(P74 on 1)
Remove the cable of the pre heater
element from the control circuit
board.
This error will appear
when after 3 minutes
of switching on the pre
heater the temperature
increase of T1 is less than
4ºC. This can also happen
when there is too much
cold air passing through
the pre heater. In that case
reduce the airflow and re-
set the malfunction
(P74 on 1).
