TXV Installation Instructions

4
Problem Symptoms Causes Corrective Action
Oversized Valve Replace with correct size valve
Incorrect Superheat Setting Adjust the superheat to correct setting
Moisture
Replace the filter driers; evacuate the system
and replace the refrigerant
Dirt or Foreign Material Clean out the material or replace the valve
Incorrect Charge Selection Select proper charge based on refrigerant type
Incorrect Bulb Location Relocate the bulb to proper location
Incorrect Equalizer Location Relocate the equalizer to proper location
Plugged Equalizer (Balanced Port Valve) Remove any restriction in the equalizer tube
Problem Symptoms Causes Corrective Action
Short of Refrigerant Add correct amount of refrigerant
High Superheat Change superheat setting
Flash Gas In Liquid Line Remove source of restriction
Low or Lost Bulb Charge Replace power element or valve
Moisture
Replace driers or evacuate the system and
replace refrigerant
Plugged Equalizer (Conventional Valve) Remove restriction in equalizer tube
Insufficient Pressure Drop or Valve Too
Small
Replace existing valve with properly sized valve
Dirt or Foreign Material Clean out material or replace valve
Incorrect Charge Selection Select correct charge
Incorrect Bulb Location Move bulb to correct location
Incorrect Equalizer Location Move equalizer to correct location
Charge Migration (MOP Only, Vapor
Charges)
Move valve to a warmer location or apply heat
tape to powerhead
Wax Use charcoal drier
Wrong equalizer type valve Use extremely equalized valve
Rod Leakage (Balanced Port Valve) Replace valve
Heat Damaged Powerhead Replace powerhead or valve
Problem Symptoms Causes Corrective Action
TXV alternately opens and closes, Bulb Location Incorrect Reposition Bulb
causing large fluctuations Valve Too Large Replace with correctly sized valve
in superheat. Incorrect Superheat Setting Adjust superheat to correct setting
Problem Symptoms Causes Corrective Action
Refrigerant Drainage/Migration
Use pump down control; install trap at the top
of the evaporator
Compressor or Suction Line in a Cold
Location
Install crankcase heater; install suction solenoid
Partially Restricted or Plugged External
Equalizer (Balanced Port Valve)
Remove restriction in equalizer tube
Problem Symptoms Causes Corrective Action
Unequal Circuit Loading Make modification to balance load
Low Load Correct conditions causing low load
Mismatched Coil/Compressor Correct match
Incorrect Distributor Install correct distributor
Evaporator Oil-Logged Increase gas velocity through coil
Valve Feeds
Too Much
1) Liquid Slugging
2) Low Superheat
3) Suction Pressure Normal or
High
Troubleshooting Expansion Valves
Superheat Is Too High -- TXV Doesn't Feed or Doesn't Feed Enough
Superheat Too Low -- TXV Feeds Too Much
1) Evaporator Temperature Too
High
2) High Superheat
3) Low Suction Pressure
Valve
Doesn't
Feed or
Doesn't
Feed
Enough
No Superheat At Start Up Only
1) Liquid Slugging
2) Zero Superheat
3) Suction Pressure Too High
Valve Feeds
Too Much At
Start Up
Erratic
pressures
and poor
performance
Superheat Appears Normal - System Performs Poorly
1) Poor System Performance
2) Low or Normal Superheat
3) Low Suction Pressure
Valve
Doesn't
Feed
Properly
Superheat Is Erratic Or Hunts