Rheem A17 Series Installation Instructions Manual page 47

10.0 DIAGNOSTICS AND TROUBLESHOOTING
10.7 Service Analyzer Chart (cont.)
ELECTRONIC EXPANSION VALVES
SYMPTOM
EXV control dc circuit failed
High superheat adjustment
Moisture causing valve to stick open
Dirt or foreign material causing valve to stick open Recover refrigerant, replace filter-drier, remove EXV and
Oversized EXV
EXV feeds too
Incorrect suction thermistor location
much refrigerant,
with low super-
heat, with low
superheat and
Low superheat adjustment
higher than normal
suction pressure
Incorrect sensing suction line temperature
Suction thermistor incorrectly calibrated
Suction pressure measured incorrectly
Refrigerant drained from flooded evaporator
Inoperable crankcase heater or crankcase heater
Compressor flood
needed
back upon start-up
Any of the causes listed under symptoms of elec-
trical problem in section 10.3
Unequal evaporator circuit loading
Superheat is low
to normal with low
Low load or airflow entering evaporator coil
suction pressure
POSSIBLE CAUSE CHECK OR REMEDIES
Verify 5Vdc to pressure transducer is present, if not,
replace EXV controller
Change the superheat offset dip switches to increase
superheat
Recover refrigerant, replace filter-drier, evacuate system
and recharge
purge with nitrogen, evacuate system and recharge
If EXV is completely clogged, use the EXV control to
open the EXV, and purge with nitrogen, replace filter
drier, and recharge
Install correct EXV
Install suction thermistor with the provided stainless steel
strap and an additional zip tie between the 10:00 and
2:00 position on suction line, and insulate
Change the superheat offset dip switches to increase
superheat
Verify suction thermistor resistance is correct and proper-
ly attached and insulated to the suction line
Replace suction thermistor assembly
After verifying lack of connectivity, replace the pressure
transducer or harness
If harness has a short, replace harness
If gauge pressure measurement and the converted volt-
age readings at the control are different replace pressure
transducer
If gauge pressure measurement and the converted
voltage readings at the control are the same, replace the
control
Install trap riser to the top of the elevator coil
Replace or add crankcase heater
Any of the solutions listed under solutions of electrical
problems in section 10.3
Ensure airflow is equally distributed through evaporator
Check for blocked distributor tubes
Ensure blower is moving proper air-flow
Remove/correct any airflow restriction
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