47
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6<03720
POSSIBLE CAUSE
5(0('<
Poor system control
using an EXV
Bad pressure reading Check transducer wiring.
Suction thermistor in wrong location Relocate thermistor.
Bad suction thermistor Replace thermistor.
Improper superheat setting (less than 5°F [-2.8°C])
Adjust EXV SH setpoint dipswitches and validate
valve operation.
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High Superheat, Low
Suction Pressure
(superheat over
15°F [8.3°C])
Moisture freezing and blocking valve
Recover charge, replace filter-drier, evacuate system,
recharge.
Dirt or foreign material blocking valve
Recover charge, replace filter-drier, evacuate system,
recharge
Low refrigerant charge Correct the charge.
Vapor bubbles in liquid line Remove restriction in liquid line. Correct the refrigerant
charge.
Remove noncondensible gases.
Size liquid line correctly.
Verify suction thermistor resistance is correct and
properly attached and insulated to the vapor line.
Incorrectly sensing vapor line temperature
Replace suction thermistor assembly.
Suction thermistor incorrectly calibrated.
If harness has a short, replace harness
If gauge pressure measurement and the converted
voltage readings at the control are the same, replace
the control.
EXV is stuck
If EXV will not open, validate EXV wiring harness and
rotor resistance between the black wire and the
other 4 wires.
Replace with correct valve.
Undersized EXV
After verifying lack of connectivity, replace the pressure
transducer or harness.
Vapor pressure measured incorrectly.
If gauge pressure measurement and the converted
voltage readings at the control are different replace
pressure transducer
Remove EXV from the system and purge with nitrogen,
replace filter drier, and recharge.
If none of the above rectifies the issue, replace EXV
and filter drier and recharge.
VSODC dc circuit failed Verify 5Vdc to pressure transducer is present. If not,
replace VSODC.
High superheat adjustment Change the superheat offset dip switches to increase
superheat.
9.3 Service Analyzer Charts (cont.)
9.0 DIAGNOSTICS & TROUBLESHOOTING
Diagnostics
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