How TXV's Improve SEER
TXVs that close when the compressor shuts off are referred to as
Hard Shut Off (HSO) TXVs.This isolates most of the charge in the
outdoor unit when the compressor is off, allowing evaporator pressure
to pull down faster on compressor start up.
TXV Problem Solving Basics
I. Underfeeding (Starving)-(Cooling Mode Only)
Symptoms: Frost on valve or indoor coil, low pressure indicated at
suction service valve, high sup normal liquid pressue.
Possible Causes: Overcharged, TXV bulb not attached or improperly
attached to suction line, check valve blocked open, blocked external
equalizer, TXV stuck open.
III. Overfeeding (Flooding)-(Cooling Mode Only)
Symptoms: Low pressure at suction valve, low superheat, high or
normal pressure at LL valve.
Possible Causes: Blocked return air, dirty RA filter, dirty coil, blower
IV. Hunting (Cooling Mode Only)
brief period and trips on compressor O/L.
Possible Causes: Check valve stuck closed.
TXVs provide better performance over the entire operating range of
the system, protects the compressor from flood back, provides
better performance with low/high refrigerant charge conditions. TXVs
are also a crucial component in achieving 13 SEER + ratings.