Carrier 40MB C Series Service Manual page 19

Remark:
Use a multimeter to test the DC
voltage between L2 port and S port of
outdoor unit. The red probe of the
multimeter connects with L2 port
while the black pin is for S port.
When the system is running normal, the
voltage will move alternately between
-50V to 50V.
If the outdoor unit has a malfunction,
the voltage will move alternately with
positive value.
While if the indoor unit has a
malfunction, the voltage will be a
certain value.
Fig. 24 – Test the DC voltage
70
Fig. 25 – Test the resistance
19
Remark:
Use a multimeter to test the
resistance of the reactor which does
not connect with capacitor.
The normal value should be around
zero ohm. Otherwise, the reactor
must have malfunction and need to
be replaced.