Page .... 24
Maritime Geothermal Ltd.
12-Feb-00
NORDIC® DX Heat Pump Trouble Shooting Guide
Fault
Possible Cause
Verification
Recommended Action
Compressor not
operating
Power Failure
Electric circuit test shows no
voltage on the line side of
compressor contactor.
Check for blown fuse at heat
pump’s disconnect box or
blown fuse
Disconnect switch open Voltmeter shows no voltage on
the line side of the compressor
contactor.
Determine why the disconnect
switch was opened, if all is
OK close the switch.
Fuse blown
At heat pump disconnect box,
voltmeter shows voltage on the
line side but not on the load
side.
Replace fuse with proper size
and type. (Time-delay) type
“D”
Check total load on system.
Low voltage
Voltmeter shows abnormally
low voltage (Below 210 v) at
heat pump disconnect switch.
Call power company.
Burned out motor
Ohmmeter shows no resistance
between common and run ter-
minals or between common
and start terminals. Note: Be
sure compressor overload has
had a chance to reset. If comp.
is hot this may take several
hours.
Determine cause and replace
motor.
Thermal overload on
compressor tripped.
Ohmmeter shows reading
when placed across R and S
terminals and infinity between
C & R or C & S.
Make sure the internal over-
load has had time to reset.
If windings are open or over-
load is faulty, replace com-
pressor.
Faulty compressor con-
tactor.
Voltage on line side with con-
tactor held closed, but no volt-
age on one or both terminals
on the load side.
Points pitted or burned.
Replace contactor.
Seized compressor due
to locked or damaged
mechanism.
Compressor attempts to start
but trips it’s internal overload
after a few seconds.
Attempt to “rock” compressor
free. If normal operation can-
not be established, replace
compressor.
Faulty run capacitor.
Check with ohmmeter for
shorts, open etc.
Replace if faulty.
