Rheem A17 Series Installation Instructions Manual page 46

10.0 DIAGNOSTICS AND TROUBLESHOOTING
10.7 Service Analyzer Chart (cont.)
FLOODING
SYMPTOM
Bad pressure reading
Suction thermistor in wrong location
Poor system con-
trol using an EXV
Bad suction thermistor
Improper superheat setting (less than 5
ELECTRONIC EXPANSION VALVES
SYMPTOM
Moisture freezing and blocking EXV
Dirt or foreign material blocking EXV
Low refrigerant charge
Vapor bubbles in liquid line
Undersized EXV
Incorrect sensing suction line temperature
Suction thermistor incorrectly calibrated
High superheat,
Suction pressure measured incorrectly
Low suction pres-
sure (superheat
o o
over 15 F [8.3 C])
EXV is stuck
EXV control board on air-handler control board
High superheat adjustment
46
POSSIBLE CAUSE
o
F [2.8
POSSIBLE CAUSE
CHECK OR REMEDIES
Check pressure transducer wiring. Replace bad trans-
ducer or wire harness
Relocate thermistor
Replace thermistor
o
C]) Adjust EXV SH setpoint dipswitches and validate valve
operation
CHECK OR REMEDIES
Recover charge, install filter-drier, evacuates system,
recharge
Recover charge, install filter-drier, evacuates system,
recharge
Correct the charge
Remove restriction in liquid line. Correct the refrigerant
charge
Remove noncondensible gases
Size liquid line correctly
Replace with correct EXV
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
voltage reading at the control are different replace the
control
Remove EXV from the system and purge with nitrogen,
replace filter drier and recharge
If EXV will not open, validate EXV wiring harness and
rotor resistance between the black wire and the other 4
wires
If none of the above rectifies the issue, replace EXV and
filter drier and recharge
Verify 5Vdc to pressure transducer is present.
If not, replace EXV control board on air-handler control
board
Charge the superheat offset dip switches to lower
superheat