Troubleshooting the TEV
HUSSMANN CORPORATION • BRIDGETON, MO 63044-2483 • Printed in USA
CONTROL VALVES Revised August 1, 1996
7 - 8
Malfunction Cause Action
Evaporator Superheat adjusted Adjust to proper superheat
Starved too high
Moisture Dehydrate and install new liquid line filter dryer
Dirt plugging strainer Remove and clean or replace
or valve mechanism
Wax Clean valve and install wax trapping dryer
Equalizer
Internal misapplied Install externally equalized TEV
External plugged Clear
Capped Install properly
Restricted Correct or repipe
Incorrect location Repipe
Flash gas upstream Head pressure too low, raise head pressure
of TEV Liquid supply line not exiting branch line from
bottom, repipe
Liquid supply line too small, repipe
Insufficient pressure Raise head pressure
drop across valve Install valve with adequate capacity at reduced
pressure
“Dead” Bulb Replace
Undersized TEV Install correct size
Evaporator Superheat adjusted Adjust to proper superheat
Flooded too low
Bulb not getting Check bulb and correct for good contact, location,
good thermal pickup and ambient influence
Moisture or dirt Clean and dehydrate and install new liquid line
holding valve open filter dryer
Oversized TEV Install correct size
Valve damage or Repair or replace
valve seat leak
Poor Uneven circuit load on Balance load (lightly loaded evaporator is
Performance multiple evaporators controlling TEV, starving loaded evaporator.)
Moisture or Dirt Clean and dehydrate and install new liquid line
filter dryer
TEV mis-sized Install correct size
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