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DIAGNOSTICS
Service Analyzer Charts
FLOODING
SYMPTOM POSSIBLE CAUSE REMEDY
Poor system control
using a TEV
Loose sensing bulb Secure the bulb and insulate�
Bulb in wrong location Relocate bulb�
Wrong size TEV Use correct replacement�
Improper superheat setting (less than 5°F [-15°C])
Replace TEV�
THERMOSTATIC EXPANSION VALVES
SYMPTOM POSSIBLE CAUSE REMEDY
High Superheat, Low
Suction Pressure
(superheat over
15°F [-9°C])
Moisture freezing and blocking valve Recover charge, install lter-drier, evacuate system,
recharge�
Dirt or foreign material blocking valve Recover charge, install lter-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�
Misapplication of internally equalized valve Use correct TEV�
Plugged external equalizer line Remove external equalizer line restriction�
Undersized TEV Replace with correct valve�
Loss of charge from power head sensing bulb Replace power head or complete TEV�
Charge migration from sensing bulb to power
head (Warm power head with warm, wet cloth�
Does valve operate correctly now?)
Ensure TEV is warmer than sensing bulb�
Valve feeds too much
refrigerant, with low
superheat and higher
than normal suction
pressure
Moisture causing valve to stick open� Recover refrigerant, replace lter-drier, evacuate system,
and recharge�
Dirt or foreign material causing valve to stick
open
Recover refrigerant, replace lter drier, evacuate system,
and recharge�
TEV seat leak (a gurgling or hissing sound is
heard AT THE TEV during the o cycle, if this is
the cause)� NOT APPLICABLE TO BLEED PORT
VALVES�
Replace the TEV�
Oversized TEV Install correct TEV�
Incorrect sensing bulb location Install bulb with two mounting straps, in 2:00 or 4:00
position on suction line, with insulation�
Low superheat adjustment Replace TEV�
Incorrectly installed, or restricted external
equalizer line
Remove restriction, or relocate external equalizer�
Diagnostics
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