Vdc Voltage Check; Ferrites - Lennox XP25-024-230-01 Installation And Service Procedure

VDC Voltage Check: Check for VDC out of Fan PWM and COM. VDC output reading is determined by the percentage of
room thermostat demand (see figure 55).
1. No voltage present – Remove wires from control and check for VDC. If there is no voltage present then replace outdoor
control.
2. Voltage present – Perform a 9-volt battery test (see below) on motor.
STATUS CODES:
None
ERROR CODES:
None
NOTE - If the outdoor fan does not operate at the correct RPM, or does not start, the system is be down by other protection
components such as the high and low pressure switches which generate error code(s).

Ferrites

Electronic cabling and wires, by virtue of their length­to­width ratios, are perfect natural antennas. In the presence of
high­speed microprocessor signals, cables will conduct, radiate, and receive unwanted high­frequency signals. Use an
insertion-loss device, such as a ferrite suppressor as shown below, to control radio-frequency (RF) interference.
BLACK LEAD
CONNECT B4 FAN MOTOR BLACK
COMMON WIRE TO 9V BATTERY
NEGATIVE TERMINAL
NEGATIVE TERMINAL
FULLY CHARGED 9V BATTERY
Figure 55. VDC Voltage Check
Figure 56. Ferrites
BROWN LEAD
CONNECT B4 FAN MOTOR WIRE
TO 9V BATTERY POSITIVE
V
TERMINAL
POSITIVE TERMINAL
Ferrites are consistently stable over time and
over wide temperature ranges, and provide
RF suppression without causing large current
losses.
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XP25