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Refrigerant loss with no visible leak

What is going on

Possible causes and checks for: refrigerant loss with no visible leak.

Likely causes

  • Relief valve weeping (debris on seat after a discharge
  • Corrosion
  • Broken seal)
  • Fusible plug failed from age/heat
  • Rupture disc burst (gauge shows pressure)
  • Stacked relief valves changing settings

Check in this order

  1. Inspect relief valve, purge line for water/debris, rupture disc gauge, replace after any discharge or at 5-year interval

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Source: General HVAC service practice — verify per model. Written in our own words; check the manual for your exact model.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.