R-Pro › Field cases › Refrigeration systems
Expansion Device Blockage (TXV / Capillary Tube)
Likely causes
Expansion valve freeze blockage from moisture
Check: Confirm blockage by measuring temperature/pressure across device
What to do: Confirm blockage by measuring temperature/pressure across device → Capillary tube: replace filter drier and backflush with nitrogen → TXV: check sensing bulb attachment and gas charge → Replace filter drier to remove moisture → Evacuate and recharge → Measure subcooling and superheat to verify normal operation
Debris/sludge clogging
Check: Capillary tube: replace filter drier and backflush with nitrogen
What to do: Capillary tube: replace filter drier and backflush with nitrogen → TXV: check sensing bulb attachment and gas charge → Replace filter drier to remove moisture → Evacuate and recharge → Measure subcooling and superheat to verify normal operation
TXV closed due to sensing bulb gas loss
Check: TXV: check sensing bulb attachment and gas charge
What to do: TXV: check sensing bulb attachment and gas charge → Replace filter drier to remove moisture → Evacuate and recharge → Measure subcooling and superheat to verify normal operation
Refrigerant pressure is normal but supply to the evaporator is blocked. Inspect expansion device for moisture or debris blockage. Recharging without removing moisture will cause rapid recurrence. Always replace the filter drier.
All 565 cases work offline in R-Pro, with error codes for 62 brands and P-T data for 108 refrigerants.
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