Carrier 40MPHA Service Manual page 29

E1 (Indoor and Outdoor Unit Communication Error) (continued)
Remarks:
• Use a multimeter to test the DC voltage between the outdoor unit's 2 port and 3 port. The red pin of multimeter connects with the 2 port
while the black pin is for 3 port.
• When the air conditioner is normal running, the voltage is moving alternately as positive values and negative values.
• If the outdoor unit has a malfunction, the voltage has always been the positive value.
• If the indoor unit has malfunction, the voltage is a fixed value.
• Use a multimeter to test the reactor resistance that does not connect with the capacitor.
• The normal value should be around zero ohm otherwise the reactor is malfunctioning.
40MPHA-03SM
Fig. 18 — Multimeter
Fig. 19 — Multimeter
Specifications subject to change without notice.
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