Troubleshooting
58
RT-SVX22J-EN
Please follow steps sequentially unless directed differently
in solution.
Table 15. Troubleshooting for direct drive plenum fan
Step
Symptom or Test
Probable Cause and Solution
1
Obstruction blocking
operation of evaporator
fan.
If obstruction is present, remove
power from unit and remove
obstruction. Check fan wheel for
damage. Remove wheel/motor
assembly if damaged.
2
Check line to line voltage
at pin 1, 2, and 3 of PPF-
IDFP.
Voltage should be same as line to line
voltage input to unit. If voltage is
same go to step 4. If not, go to step 3.
3
Verify continuity across
fuse FU31, FU32, and
FU33.
Replace fuse if continuity is not
present.
4
Measure DC voltage
across pin Vt and com on
MMC or note voltage on
ECM display.
Voltage should be greater than 1.0
VDC. If voltage is greater the 1.0, go
to step 8. If not, turn knob on MMC
counter-clock wise 1 turn and check
voltage again. For units with ECM
board increase the output voltage by
3.0 VDC and check voltage again. If
no change in voltage, go to step 5
5
Check for 24VAC across
pins A and B on F relay.
For units with no F, go to
step 7.
If voltage is not present, verify
thermostat wiring. Go to step 4. If
voltage is present, go to step 6.
6
Check for 10VDC across
pin 9 on F relay an pin 8
of PPM-IDFC.
If voltage is not present, check wiring
to F relay. Correct wiring if needed.
Go to step 4. If wiring is correct,
replace relay.
7
Measure DC voltage
across pin Vt and com on
MMC or note voltage on
ECM display.
Voltage should be greater than 1.0
VDC. If voltage not present, replace
MMC / ECM board.
8
Verify VDC is same
across Vt and com on
MMC (or ECM display)
and pin 1 and pin 8 on
PPM-IDFC.
If voltage is not same, check for
correct wiring. If voltage is the same
go to step 9.
9
Verify correct wiring
connections at KL3 in the
motor.
If wiring is correct, replace motor.
Summary of Contents for Precedent THC036E
Page 37: ...Installation RT SVX22J EN 37 Figure 51 Examples...
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