CARE

Carel LSH

Critical

MPXPRO — Low superheat alarm, risk of liquid refrigerant return to the compressor

Carel LSH: Low superheat alarm, risk of liquid refrigerant return to the compressor This fault typically halts operation and needs immediate attention.

Possible causes

Electronic expansion valve opened too far or PID parameters (P4-P6) incorrectly tuned
tGS probe or pressure probe PEu/tEu incorrectly positioned or faulty

Check steps

Check threshold P7 (LowSH) and set point P3 (superheat)
Check position and insulation of tGS probe and pressure probe at evaporator outlet

Affected parts

E2V/PWM electronic expansion valve
tGS temperature probe
PEu pressure probe

Safety note

Refrigerant circuit is pressurized - depressurize and disconnect mains power before servicing

Source: Carel resmi servis kilavuzu (bagimsiz cift-dogrulandi) — Carel MPXPRO User Manual +0300055EN rel.1.5 (05.05.2017) [text identical to rel.1.6 on this point] — Table 9.b "Table of alarms", §9.2 Alarms, p.57: "LSH | Low superheat alarm" with Compressor column = OFF and Network solenoid valve column = √ (closed); and §6.10 "LowSH Low superheat", p.47: "a low superheat thr…

Reviewed by Anıl Güzeldemir — in the refrigeration machine room since 2006, developer of Enthalio.

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