Table 6-4 — Troubleshooting the TEV
CONTROL VALVES
September 1, 1997
6 - 8
HUSSM ANN CORPORATION • BRIDGETON, M O 63044-2483 • Printed in USA
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 re-pipe
Incorrect location
Re-pipe
Flash gas upstream
Head pressure too low, raise head pressure
of TEV
Liquid supply line not exiting branch line from
bottom, re-pipe
Liquid supply line too small, re-pipe
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
Return to Contents