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