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Economizer Valve Stuck → Efficiency Loss

Likely causes

Economizer EEV coil open-circuit or actuator malfunction

Check: Measure EEV coil resistance: normal 20–40 Ω. Infinite = coil defective. Check controller output terminal voltage

What to do: Replace coil → manual open/close test to check mechanical seizure → replace valve assembly with OEM parts if seized

Foreign particles or moisture in refrigerant cause valve seat seizure (full-closed seizure causes 10–15% efficiency drop)

Check: Check pressures across valve: intercooler pressure should be midpoint between suction/discharge; deviation indicates fault

What to do: Recover refrigerant → replace drier and strainer → flush economizer line → replace valve assembly → recharge

Controller economizer output signal at 0 V — wiring short or PCB failure

Check: Force economizer output from controller service menu → check DC voltage at output terminal (0 V = PCB defective)

What to do: Measure wiring insulation resistance to locate short → repair wiring → replace PCB if PCB itself is defective

Field tip

When the economizer is inactive, discharge temperature rises 5–8 °C above normal — use this as a quick field indicator for valve seizure.

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