Fault codes covered
38-54
This diagnostic checks to ensure the compressor is running in the correct direction and pumping properly. Once the compressor speed is >400rpm, the compressor has up to 30 seconds to increase the pressure differential (discharge pressure – suction pressure) by 20psi. If this pressure differential is not met, code 38-54 sets by locking operation for 30 minutes.
The most likely cause of this fault is the compressor leads being wired incorrectly. Check wire colors against wiring diagram to ensure UVW wires are attached to the correct terminals. Less likely but still possible is compressor motor shaft breakage allowing compressor motor to rotate but is disconnected from compression mechanism.
Fan Motor Faults General Info
The fan motor used on these models require 5 wires. 240~373 VDC is supplied through Pin 1 of 3 pin connector (VDC) and Pin 1 of 4 pin connector (GND). Pin 2 of 4 pin connector is Vcc signal for IC power supply (~15Vdc). Pin 3 of 4 pin connector is Vsp signal, which is 0-5VDC input speed control. Pin 4 of 4 pin is FG or feedback signal, sending rpm information back to VFD. The motor is controlled using a closed loop control where variable speed is increased or decreased by VFD depending on the RPM command from PCM to VFD along with actual RPM information read through FG pin. Use Table 6 to confirm damaged electronics within fan motor. Note – winding resistance cannot be measured on fan motor due to embedded electronics. Note – resistances are approximate, temperature may affect measurements so only declare motor bad if results differ greatly from values in Table 6 . Though the fan motor has internal current protection, an external replaceable fuse is located on VFD for short circuit protection. See wiring diagram for fuse replacement specifications.
Source: ACHPVSR454-02SM troubleshooting pages.