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TROUBLESHOOTING GUIDE FOR LOCKOUT CONDITIONS
If
the heat
pump
goes
into lockout
on
a
high or
low
pressure
switch,
the
cause
of
the
lockout
can be
narrowed down
by
knowing
the
operating mode
and
which
pressure
switch
the
unit
locked out
on.
The
following
table
will
help track down
the
problem
once
this
information
is
known.
NOTE:
A
lockout condition
is
a
result
of
the heat
pump shutting
itself off
to
protect
itself.
Never
bypass the
lockout
circuit.
Serious damage can be caused
by the
system
operating
without lockout
protection.
L
Rattles
and
Vibrations
Check
for
loose
screws, panels,
or
internal components.
Tighten
and
secure. Copper
piping
could
be
hitting
the
metal
surfaces.
Carefully
readjust by bending
slightly.
Noisy
Operation
(Continued)
Water
and
Airborne
Noises
Undersized
ductwork
will
cause
high airflow
velocities
and
noisy
operation.
Excessive water through
the
water-cooled
heat
exchanger
will
cause
a
squealing
sound.
Check
the
water
flow
to
ensure adequate
flow
for
good operation,
while eliminating
the
noise.
Dirty Air Filter
Check
filter.
Clean or
replace
if
found
dirty
Airflow
Lack of
adequate
airflow
or improper
distribution of
air.
Check
the
motor
speed and
duct
sizing.
Check
the
filter,
it
should
be
inspected
every month
and changed
if dirty.
Check
for
closed registers.
Remove
or
add resistance
accordingly.
Evaporator
B
lower
Motor
Tripping
Off
on Overload
Check
for
overheated
evaporator
blower motor
and
tripped
overload.
Replace motor
if
necessary.
Evaporator
(air coil)
ices
over
Unit
Operating
at
Too
Low
a
Room Temperature
If
room temperature
drops
below 65
degrees, the
evaporator may
lce over
Unit Not Level
or Pitched
Correctly
Level vertical
units,
and
horizontal units
which
use
bottom
condensate
drain.
Pitch horizontal units that
use side condensate
drain.
Water drips
from unit
Condensate
Drain Line
Kinked or
Plugged
Clean
condensate
drain.
High
Pressure
(Head)
(Condenser/Air
Side)
-Lossflack
ofairflow
through air
coil
(dfuty
air
filter,
closed vents,
blower,
restricted
ductwork,
etc.)
-High
air temperature entering
heat
pump
-Dirty
(fouled)
air
coil
-Extremely
high water temperature
to
the
evaporator,
raising
compressor capacity
and
overloading
condenser
-Overcharged refrigerant
circuit
Heating
Low
Pressure
(Suction)
(Evaporator/Earth
Coupled Side)
-Loss/lack
of
flow
through
earth
coupled
coil
-Low
fluid
temperature operation
in
the earth
loop
-Freezing
fluid
in
heat
exchanger (lack
of
antifreeze)
-Undercharged/overcharged refrigerant
circuit
-Expansion valve/sensing
bulb malfunction
High
Pressure
(Head)
(Condenser/Earth
Coupled Side)
-Loss/lack
of
water
flow
-High
fluid
temperature operation
in
the
earth
loop
-Dirty
(fouled)
condenser
coil
-Overcharged refrigerant
circuit
Cooling
Low
Pressure
(Suction)
(Evaporator/Air
Side)
-Loss/lack
of
airflow
through air
coil
(dirty
filter,
closed vents,
blower, restricted
ductwork,
etc.)
-Low
air temperature entering
the heat
pump (thermostat setpoint
too
low,
etc.)
-Air coil
freezing up
(low airflow,
lack
of
charge,
etc.)
-Undercharged/overcharged refrigerant
circuit
-Expansion valve/sensing
bulb malfunction
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