Service manual

2-14
AY-ZP35PR
3.3.1 Details of troubleshooting procedure for PAM
1) PAM shutdown due to error

DC voltage of 350 V or higher (detection circuit input voltage of about 9.2 V or higher) [IC8 pin (4)]
–When an error is detected





–When an error is detected



2) PAM error indication
In case of error “1)”
– An error signal is sent to the indoor unit as soon as an error is generated.




In case of error “2)”
– An error signal is sent to the indoor unit as soon as an error is judged.



(Compressor OFF or Thermostat OFF from remote control)

In addition to conventional error-generating reasons, there is a possibility that the PAM IGBT does not turn ON even if the com-
pressor is operating.
In that case, the DC voltage does not rise even though the compressor is operating, and lowers to the 180-VDC level.
–Check items



4. Explanation of IPM drive circuit
The IPM for compressor drive is made by Mitsubishi Electric.
The power supply for the IPM drive, the shunt resistance for over current detection, etc., are provided outside the IPM (control PCB).
4.1. IPM drive power supply circuit
The power supply for the upper-phase IGBT (HU, HV, HW) drive employs a bootstrap system, and provides power to the upper-phase
IC.
The 15-V power supply for the lower-phase IC is provided by the control printed circuit board (PCB).
4.1.1 Brief explanation of bootstrap system (single power drive system)
To supply power to the upper-phase IC, the microcomputer (IC1) turns ON the lower-phase IGBT (LU, LV, LW).
-
tor with a 15V current.