R-Pro › Field cases › Refrigeration systems
TXV Internal Defect (Diaphragm or Spring Fault)
Likely causes
Diaphragm gas leak causing loss of valve control
Check: Recover all refrigerant
What to do: Recover all refrigerant → Replace TXV with same refrigerant, capacity, and orifice size → Replace filter drier at the same time → Re-install sensing bulb (4–8 o'clock position, insulated) → Evacuate, recharge, run 20 minutes, then measure superheat
Spring aging prevents maintaining set point
Check: Replace TXV with same refrigerant, capacity, and orifice size
What to do: Replace TXV with same refrigerant, capacity, and orifice size → Replace filter drier at the same time → Re-install sensing bulb (4–8 o'clock position, insulated) → Evacuate, recharge, run 20 minutes, then measure superheat
Partial debris blockage of internal orifice
Check: Replace filter drier at the same time
What to do: Replace filter drier at the same time → Re-install sensing bulb (4–8 o'clock position, insulated) → Evacuate, recharge, run 20 minutes, then measure superheat
If hunting persists with normal bulb contact and load conditions, the TXV has an internal defect. Replace the TXV. Always use a TXV matched to the refrigerant type and system capacity. Using an R404A TXV in an R22 circuit causes loss of control.
All 565 cases work offline in R-Pro, with error codes for 62 brands and P-T data for 108 refrigerants.
Open R-Pro →Related cases
- Aging Room Humidity Control Failure (Unable to Maintain 85~95%RH)
- Ethylene Buildup in Meal Kit/Produce Warehouse — Over-Ripening Due to Ventilation Failure
- End-Zone Temperature Rise (Uneven Cooling)
- Air Curtain Weakening
- Excessive Temperature Rise After Defrost
- Excessive Heat Load from Direct Sunlight or Lighting