Rheem FO13C Series Installation Instructions Manual page 45

Service Analyzer Charts
THERMOSTATIC EXPANSION VALVES (cont.)
SYMPTOM
Refrigerant drainage from fl ooded evaporator
Inoperable crankcase heater or crankcase heater
Compressor fl ood
needed
back upon start-up
Any of the causes listed under symptoms of
Electrical problems on page 45
Unequal evaporator circuit loading
Superheat is low to
normal with low
Low load or airfl ow entering evaporator coil
suction pressure
Expansion valve is oversized
Sensing bulb is aff ected by liquid refrigerant or
refrigerant oil fl owing through suction line
Superheat and
Unequal refrigerant fl ow through evaporator
suction pressure
circuits
fl uctuate (valve is
hunting)
Moisture freezing and partially blocking TEV
External equalizer line not connected or line
plugged
Valve does not
Sensing bulb lost its operating charge
regulate at all
Valve body damaged during soldering or by
improper installation
POSSIBLE CAUSE
DIAGNOSTICS
REMEDY
Install trap riser to the top of the evaporator coil.
Replace or add crankcase heater.
Any of the solutions listed under solutions of Electrical
problems on page 45
Ensure airfl ow is equally distributed through evaporator.
Check for blocked distributor tubes.
Ensure blower is moving proper air CFM.
Remove/Correct any airfl ow restriction.
Install correct TEV.
Relocate sensing bulb in another position around the
circumference of the suction line.
Ensure sensing bulb is located properly.
Check for blocked distributor tubes.
Recover refrigerant, change fi lter-drier, evacuate system,
and recharge.
Connect equalizer line in proper location, or remove any
blockage.
Replace TEV.
Replace TEV.
45