Carrier 42QFD048D8S Service Manual page 96

3. Outdoor DC Fan IPM Board(for some double fan models)
Power on and when the unit is in standby, measure the voltage of CON1, pin1-pin2 and pin3-pin2 of CN1 in DC motor
driver board. If the value of the voltage is not in the range showing in below tables, the outdoor main PCB must has
problems and need to be replaced.
Part
CON1
CN1
CN2
FAN1
FAN2
CN1 Communication with main PCB
Drive Chip
FAN1
IPM for DC
Fan
Description
Power input for the PCB
Communication with main PCB
Test port
UVW output for DC fan motor
UVW output for DC fan motor
5
No.
1
2
3
4
5

CN2 CN1
EEPROM
Parameter
192-380V/DC
DC
5V/DC
4 3 2 1
Signal Voltage
Vcc 13.5-16.5V
GND 0V
Vsp 0~6.5V
FG 13.5-16.5V
--- ---
Troubleshooting 
CON1
FAN2
Rectifier
Remark
For debugging board