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OPERATING MODE
Electric
1-Speed A/C
2-Speed A/C, Low Speed
2-Speed A/C, High Speed
1-Speed HP
1-Speed HP
2-Speed HP, Low Speed
2-Speed HP, Low Speed
2-Speed HP, High Speed
2-Speed HP, High Speed
Continuous Fan
Continuous Fan
Continuous Fan
** AC Voltages less than 18 are not recognized by the ICM.
voltage applied to low-voltage circuit, or a direct secondary short.
When there is a high current drawn on transformer, it is most likely
because transformer has been shorted or system is trying to draw
more va than transformer rating allows. When fuse blows because
of high voltage, the system has mixed high- and low-voltage
signals.
1. Check transformer and thermostat wiring. (See Fig. 24 and
26.) Be sure transformer is not shorting out because
thermostat wires are miswired.
2. Check wiring of sequencers. (See Fig. 24 and 26.) Be sure
low-voltage and high-voltage wiring are connected to
proper sequencers.
3. Check VA draw on transformer. If VA draw is more than
VA rating of transformer, fuse will blow. If this is the case,
replace transformer with one that has a higher VA rating.
XIV. TROUBLESHOOTING ICM2 FAN MOTOR
A. If Motor Does Not Run:
1. With power turned off, check all plugs and receptacles on
circuit board and at motor for any deformation that may
cause a bad connection. Be sure all plugs are placed fully
seated.
2. Verify that there is approximately 230v.
3. Verify that there is a low-voltage control signal to motor.
The motor receives its control signals through the 12-pin
motor plug PL1. The voltage output of each pin in plug will
be different for each mode of operation. Table 9 lists circuit
board screw terminals that have 24 vac present (powered by
thermostat) and lists voltage that is present at each pin of
12-pin plug for each operating mode. Tests should be taken
between points listed and common (C screw terminal). If all
values of any 1 of operating modes check OK and motor
fails to run, then motor is defective and should be replaced.
B. If Motor Does Not Run Smoothly:
First verify that the cause is not an out-of-balance or damaged
blower wheel. If it is not blower wheel, motor is defective and
should be replaced.
C. If Motor Shaft Does Not Rotate Smoothly:
When manually turning shaft of ICM, the shaft does not rotate
smoothly. The shaft has steps during rotation referred to as motor
cogging. The cogging is caused by permanent magnets passing
each pole of motor. However, shaft should not require excessive
force to turn. If shaft is VERY difficult to turn, motor control or
bearings have failed and motor must be replaced.
→ TABLE 9—FK4C MOTOR CONTROL TEST VALUES
(WITH 16-PIN CONNECTOR AT MOTOR UNPLUGGED)
SCREW TERMINALS
HAVING 24 VAC
Heating
R
W1
W2
Cooling
R
Y/Y2
G
Cooling
R
Y1
G
Cooling
R
Y/Y2
G
Cooling
R
Y/Y2
G
Heating
R
Y/Y2
G
Cooling
R
Y1
G
Heating
R
Y1
G
Cooling
R
Y/Y2
Y1
Heating
R
Y/Y2
Y1
Low
R
G
Medium
R
G
High
R
G
** VOLTAGES—12-PIN PLUG PL1
W1
G
Pin 7
Pin 1
24 vac
0
0
24 vac
0
24 vac
Y1
0
24 vac
O
0
24 vac
0
24 vac
O
0
24 vac
0
24 vac
G
O
0
24 vac
G
0
24 vac
0
24 vac
0
24 vac
0
24 vac
D. If Motor Does Not Stop Running
1. Check for good ground between motor ground lead and
transformer common lead.
2. If motor continues to run, remove all thermostat wires. If
motor stops, check thermostat wiring to thermostat or
outdoor unit for shorts or miswire.
XV. CONDENSED VERSION OF TROUBLESHOOTING
FK4C AND FV4A MOTOR AND CONTROLS
This section provides a quick summary of how to troubleshoot the
FK4C and FV4A. If more information is needed, refer to appro-
priate sections of this service manual.
+ MOTOR
- If motor is hard to turn manually, replace motor.
- If motor does not run, check the components listed below
according to their instructions.
- If motor runs in some operation modes and not in others,
check for a good ground connection between motor ground lead
and circuit board screw marked "ground screw" and check the
room thermostat and wiring harness according to instructions
listed below.
+ CIRCUIT BOARD
- Check 5-amp fuse.
- Check for 24v between SEC1 and SEC2. If no voltage is
present, check the transformer.
- Check for burn traces or burnt components. If burn spots are
present, replace board.
+ ROOM THERMOSTAT
- Remove thermostat wires from the circuit board.
- Jumper screw terminals (1 at a time) R-G, R-Y/Y2, R-Y1,
and R-W1. If motor runs in all cases, thermostat is bad. Replace
thermostat. If motor does not run, or runs in some cases but not in
others, continue by checking the wiring harness.
+ WIRING HARNESS
- Shut off power to unit.
- Remove 5-pin plug from motor.
CAUTION: Never remove 5-pin high voltage plug from
the motor with the power on.
- Remove 16-pin plug from motor.
- Replace 5-pin plug and turn on power.
—34—
C
C
R
Y/Y2
Pin 9
Pin 10
Pin 8
Pin 2
0
0
24 vac
0
0
24 vac
- 12 vdc
0
0
24 vac
0
0
24 vac
- 12 vdc
0
0
24 vac
- 12 vdc
0
0
24 vac
- 12 vdc
0
0
24 vac
0
0
24 vac
0
0
24 vac
- 12 vdc
0
0
24 vac
- 12 vdc
0
0
24 vac
0
0
24 vac
- 12 vdc
0
0
24 vac
Y1
Pin 3
0
0
0
- 12 vdc
- 12 vdc
0
0
0
- 12 vdc
0
- 12 vdc
- 12 vdc
- 12 vdc
0
0
0
0
-12 vdc
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Table of Contents
Troubleshooting
