Maritime Geothermal EMWT-65-HACW-P-1T, Installation And Service Manual

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01 MAR 2012 Page 29 000662MAN-03
OPERATION TROUBLESHOOTING - COOLING MODE
Fault Possible Cause Verification Recommended Action
High Discharge
pressure Unit is overcharged.
(Only possible if unit has
been opened in the field
and incorrectly charged). High sub-cooling, low delta T
across water coil. Remove 1/2lb of refrigerant at a
time and verify that the discharge
pressure reduces.
High Suction
Pressure
(may appear to
not be pumping) TXV adjusted too far
open. Verify superheat. It should be be-
tween 8-12°F (3-6°C). Superheat
will be low if TXV is open too far. Adjust TXV to obtain 8-12°F(3-6°C)
superheat.
TXV stuck open. Adjusting the TXV does not affect
the superheat or the suction pres-
sure. Low super heat and dis-
charge pressure. Adjust the TXV all the way in and out a
few times to loosen it. Replace TXV if
this does not work.
Leaking reversing valve. Reversing valve is the same tem-
perature on both ends of body,
common suction line is warm,
compressor is running hot. Replace reversing valve.
Low Suction
Pressure Aquastat set too low. Verify aquastat setting Raise aquastat setting to recom-
mended value of
45°F (7°C)
Low or no flow in heat ex-
changer to buffer tank
circuit. Check that isolation flanges and
any ball valves are open. Verify
115VAC to pump. Check gauges
for pressure drop. Ensure flow path is unrestricted.
Replace pump if faulty.
Faulty internal circulator
select relay. Internal hot circulator is pumping
instead of internal cold circulator Replace relay.
Low or no refrigerant
charge. Entering air temperature and air-
flow are good but suction is low.
Check static refrigeration pressure
of unit for very low value. Locate the leak and repair it.
Spray nine, a sniffer and dye are
common methods of locating a
leak.
Faulty compressor, not
pumping. Pressures change only slightly
from static values when compres-
sor is started. Replace compressor.
Compressor
frosting up
See Low Suction
Pressure in this section.
TXV frosting up TXV stuck almost closed
or partially blocked by for-
eign object. Adjusting the TXV does not affect
the superheat or the suction pres-
sure. Adjust the TXV all the way in and out a
few times to loosen it. Replace TXV if
this does not work.
Random Low
Pressure trip
(does not occur
while there) Faulty compressor
contactor. Points pitted or burned. Contactor
sometimes sticks causing the
compressor to run without the fan,
tripping the low pressure control. Replace contactor.
Intermittent Cold Indoor
Loop circulator (heat ex-
changer to ColdTank). Verify wiring is good Correct the wiring or replace the
circulator.
TXV stuck almost closed
or partially blocked by for-
eign object. Adjusting the TXV does not affect
the superheat or the suction pres-
sure. TXV may be frosting up. Adjust the TXV all the way in and out a
few times to loosen it. Replace TXV if
this does not work.