Fault codes covered
88-31, 88-71
The VFD measures the compressor current value internally. If the compressor current measurement is not reported to VFD, it will shut down and attempt a restart after 5 minute compressor protection timer expires. Operating VFD without monitoring compressor current may result in compressor damage. Three occurrences of code 88-31 within a 4 hour period will result in 88-71 malfunction and 4 hour lockout. While this fault or malfunction is active the unit is inoperable. This malfunction, once set, is unlikely to go away and indicates VFD damage. Manually power cycle outdoor unit with disconnect, if malfunction persists replace VFD.
Source: ACHPVSR454-02SM troubleshooting pages.