Service manual
5-2T-294-01
CONDITION
POSSIBLE CAUSE
REMEDY/
REFERENCE
SECTION
5.4 UNIT WILL NOT HEAT OR HAS INSUFFICIENT HEATING
Start-Stop switch (ST) OFF or defective Check
No power to unit
Circuit breaker (CB) OFF or defective Check
N
o
p
o
w
e
r
t
o
u
n
i
t
External power source OFF Turn on
Circuit breaker (CB) or fuse (F) defective Replace
T ransformer defective (TR) Replace
No control power
Evaporator fan internal motor protector (IP) open 6.16
N
o
c
o
n
t
r
o
l
p
o
w
e
r
Heat relay (TH) defective Check
Heater termination thermostat (HTT) open 6.14
Heater(s) (DHBL, DHBR, DHTL, DHTR) defective 6.15
Heater contactor (HR) or coil defective Replace
Evaporator fan motor(s) defective or rotating backwards 6.16/6.17
Unit will not heat or has
Evaporator fan motor contactor (EF or ES) defective Replace
U
n
i
t
w
i
l
l
n
o
t
h
e
a
t
o
r
h
a
s
insufficient heat
Temperature controller malfunction 5.9
Defective wiring Replace
Loose terminal connections T ighten
Low line voltage 2.4
5.5 UNIT WILL NOT TERMINATE HEATING
Temperature controller improperly set Reset
U
n
i
t
f
a
i
l
s
t
o
s
t
o
p
h
e
a
t
i
n
g
Temperature controller malfunction 5.9
U
n
i
t
f
a
i
l
s
t
o
s
t
o
p
h
e
a
t
i
n
g
Heater termination thermostat (HTT) remains closed along
with the heat relay (TH)
6.14
5.6 UNIT WILL NOT DEFROST PROPERLY
Defrost timer malfunction 3.1.4
Loose terminal connections T ighten
Will not initiate defrost
Defective wiring Replace
W
i
l
l
n
o
t
i
n
i
t
i
a
t
e
d
e
f
r
o
s
t
automatically
Defrost termination sensor (DTS) defective or heat
termination thermostat (HTT)open
Replace
Heater contactor (HR) or coil defective Replace
W
i
l
l
n
o
t
i
n
i
t
i
a
t
e
d
e
f
r
o
s
t
m
a
n
u
a
l
l
y
Manual defrost switch (MDS) defective Replace
W
i
l
l
not
i
n
i
t
i
ate
d
e
f
rost manua
l
l
y
Defrost termination sensor (DTS) open 4.4.6
Initiates but relay (DR) drops out Low line voltage 2.4
I
n
i
t
i
a
t
e
s
b
u
t
d
o
e
s
n
o
t
d
e
f
r
o
s
t
Heater contactor (HR) or coil defective Replace
I
n
i
t
i
ates
b
ut
d
oes not
d
e
f
rost
Heater(s) (DHBL, DHBR, DHTL, DHTR) burned out 6.15
Frequent defrost Wet load Normal