Rheem A17 Series, Installation Instructions Manual

Page: 46 / 52

46
10.0 DIAGNOSTICS AND TROUBLESHOOTING
10.7 Service Analyzer Chart (cont.)
Diagnostics
FLOODING
SYMPTOM POSSIBLE CAUSE CHECK OR REMEDIES
Poor system con -
trol using an EXV
Bad pressure reading Check pressure transducer wiring. Replace bad trans -
ducer or wire harness
Suction thermistor in wrong location Relocate thermistor
Bad suction thermistor Replace thermistor
Improper superheat setting (less than 5
o
F [2.8
o
C]) Adjust EXV SH setpoint dipswitches and validate valve
operation
ELECTRONIC EXPANSION VALVES
SYMPTOM POSSIBLE CAUSE CHECK OR REMEDIES
High superheat,
Low suction pres
-
sure (superheat
over 15
o
F [8.3
o
C])
Moisture freezing and blocking EXV Recover charge, install filter-drier, evacuates system,
recharge
Dirt or foreign material blocking EXV Recover charge, install filter-drier, evacuates 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
Undersized EXV Replace with correct EXV
Incorrect sensing suction line temperature Verify suction thermistor resistance is correct and proper -
ly attached and insulated to the suction line
Suction thermistor incorrectly calibrated Replace suction thermistor assembly
Suction pressure measured incorrectly 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
EXV is stuck 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
EXV control board on air-handler control board Verify 5Vdc to pressure transducer is present.
If not, replace EXV control board on air-handler control
board
High superheat adjustment Charge the superheat offset dip switches to lower
superheat