R-Pro › Field cases › Air conditioning
AC Pressure Sensor (High/Low) Fault
Likely causes
Identify sensor type (switch / analog transducer)
Check: Switch type = on/off at threshold (resistance 0 Ω ↔ ∞). Transducer = with 5VDC supply, outputs 0.5–4.5V proportional. Refer to manual for pressure → voltage table. Compare actual pressure (manifold) vs PCB reading — deviation >±10% = sensor bad.
What to do: Measure actual manifold pressure and PCB reading simultaneously. Deviation >±10% = sensor bad. Replace with same spec and pinout. Transducer = verify DC 5V supply, measure output. After replacement, run learning or self-diagnostic mode to confirm recognition.
Faulty high-pressure sensor = false high-pressure cutouts. Faulty low-pressure = false undercharge diagnosis. Replace with same spec/pinout. Some models legally require these protections — never bypass.
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