HVACopediaCarrier · Heat pump
57 Suction pressure transducer fault
What the control is telling you
Amber STATUS light flashes 57. The suction pressure transducer (SPT) signal is missing or out of range. Type: Fault; reset: None (fix the transducer).
Applies to: Carrier Infinity 18VS variable speed heat pump 25VNA8 (AOC control + inverter)
Likely causes
- Transducer plug not connected to the AOC board
- Broken or loose harness wire
- Transducer damaged by an electrical short
- Transducer damaged by heat during brazing
Test and repair steps
- Check the plug and harness.
- Compare the transducer reading with a gauge at the service valve (transducer chart in the manual).
- Correct any electrical short, then replace the transducer if readings do not match.
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Source: Carrier 25VNA8 / 24VNA9 Service Manual, Table 6 Fault Code Actions, p.20. Summarized in our own words; check the original manual for your model.
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