Diagnostics
40
8
Code
Cooling
Hea
ting
Description
W
arning
Err
or
Possible c
auses / C
hecks
616
X
X
Outlet w
at
er t
emper
atur
e sensor fault
y
(THM)
NA
Er
ror can be r
eset via S61, DDC or
po
w
er off
Br
oken or shor
t in sensor wir
e
Possible bad c
onnec
tion a
t c
on
trol boar
d
If the pr
oblem persists
, c
on
tac
t A
T
617
X
X
Inlet w
at
er t
emper
atur
e sensor fault
y
(THR)
NA
Er
ror can be r
eset via S61, DDC or
po
w
er off
Br
oken or shor
t in sensor wir
e
Possible bad c
onnec
tion a
t c
on
trol boar
d
If the pr
oblem persists
, c
on
tac
t A
T
618
X
X
Condenser outlet t
emper
atur
e sensor
fault
y (
TCN)
NA
Er
ror can be r
eset via S61, DDC or
po
w
er off
Br
oken or shor
t in sensor wir
e
Possible bad c
onnec
tion a
t c
on
trol boar
d
If the pr
oblem persists
, c
on
tac
t A
T
620
X
X
Condenser inlet t
emper
atur
e sensor fault
y
(TG
)
NA
Er
ror can be r
eset via S61, DDC or
po
w
er off
Br
oken or shor
t in sensor wir
e
Possible bad c
onnec
tion a
t c
on
trol boar
d
If the pr
oblem persists
, c
on
tac
t A
T
628
X
X
Gas v
alv
e ener
giz
ed with ig
nition malfunc
-
tion c
ode (E 12) ac
tiv
e
NA
Er
ror can be r
eset via S61, DDC or
po
w
er off
If the pr
oblem persists
, c
on
tac
t A
T
629
X
X
Ig
nition malfunc
tion
No v
oltage supplied t
o gas v
alv
e fr
om
Fen
w
al af
ter 120 sec
onds fr
om call f
or
flame b
y the S61 boar
d
W
ar
ning will aut
oma
tically r
eset if gas v
alv
e is
po
w
er
ed within 10 minut
es fr
om call f
or flame
or
, if af
ter 5 min of oper
ation the w
ar
ning is
gener
at
ed
, then it will r
eset if ther
e is no longer
call f
or oper
ation
Er
ror can be r
eset via S61, DDC or
po
w
er off
Possible blocked flue passage
Bad or fault
y air pr
essur
e diff
er
en
tial swit
ch - possibly stuck closed or stuck open
Bad or fault
y pr
e-mix blo
w
er assy mot
or
Debr
is on blo
w
er wheel pr
ev
en
ting full air flo
w
Cr
acked or clogged air tubes c
onnec
ting blo
w
er assy t
o pr
essur
e diff
er
en
tial swit
ch
Possible loss of flame sensing af
ter 5 minut
es of oper
ation
Possible gas v
alv
e issue af
ter 5 minut
es of oper
ation
If the pr
oblem persists
, c
on
tac
t A
T
631
X
W
at
er t
emper
atur
e abo
ve oper
ational
limits in hea
ting mode
FW v
er
. 3.026 or la
ter
W
ar
ning will r
eset aut
oma
tically when t
empe
-
ra
tur
e dr
op b
y 3,6 °F belo
w limit
NA
Ligh
t load c
onditions
Lo
w w
at
er flo
w
Oper
ation in c
onjunc
tion with 3r
d par
ty boilers in loop c
onfigur
ation tha
t allo
ws
hott
er w
at
er t
o flo
w thr
ough units
If the pr
oblem persists
, c
on
tac
t A
T
632
X
W
at
er t
emper
atur
e belo
w oper
ational
limits in c
ooling mode
FW v
er
. 3.026 or la
ter
W
ar
ning will r
eset aut
oma
tically when t
empe
-
ra
tur
e incr
eases b
y 3,6 °F abo
ve limit
NA
Ligh
t load c
onditions
Lo
w w
at
er flo
w
If the pr
oblem persists
, c
on
tac
t A
T
644
X
X
TA1 t
emper
atur
e sensor fault
y (wir
e is
labeled T
CN)
NA
Er
ror can be r
eset via S61, DDC or
po
w
er off
Br
oken or shor
t in sensor wir
e
Possible bad c
onnec
tion a
t c
on
trol boar
d
If the pr
oblem persists
, c
on
tac
t A
T
646
X
High hot w
at
er inlet t
emper
atur
e
W
ar
ning will r
eset aut
oma
tically when t
empe
-
ra
tur
e dr
ops b
y 9.0 °F belo
w limit
NA
Ligh
t load c
onditions
Lo
w w
at
er flo
w
Possible applica
tion or piping issues if w
or
king in c
onjunc
tion with 3r
d par
ty
boilers allo
wing hott
er w
at
er t
o en
ter hea
t pump
If the pr
oblem persists
, c
on
tac
t A
T
647
X
Lo
w hot w
at
er inlet t
emper
atur
e
Reset is aut
oma
tic when the tr
igger
ing
condition c
eases
, or 430 s af
ter the w
ar
ning w
as
gener
at
ed
Reset is aut
oma
tic when the
trigger
ing c
ondition c
eases
Building load c
onditions g
rea
ter than output of unit
Possible c
old w
at
er star
ting c
onditions
If the pr
oblem persists
, c
on
tac
t A
T
648
X
Hot w
at
er diff
er
en
tial t
oo high
Reset is aut
oma
tic when the tr
igger
ing
condition c
eases
, or 20 minut
es af
ter the c
ode
is gener
at
ed
Reset is aut
oma
tic when the
trigger
ing c
ondition c
eases
Lo
w w
at
er flo
w
Failing t
emper
atur
e sensor or sensor not mak
ing good c
on
tac
t
If the pr
oblem persists
, c
on
tac
t A
T
649
X
X
Auxiliar
y hea
ting boar
d not r
ec
og
niz
ed
Reset is aut
oma
tic when the tr
igger
ing c
ondi
-
tion c
eases
Reset is aut
oma
tic when the
trigger
ing c
ondition c
eases
Bad cable c
onnec
tion bet
w
een boar
ds
Inc
or
rec
t c
on
trol boar
d par
amet
ers
If the pr
oblem persists
, c
on
tac
t A
T
