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, replace circuit board.
3. If motor continues to run, remove the 7-pin plug. If motor
continues to run, replace motor.
Step 7—Condensed Version of Troubleshooting FK4B
Motor and Controls
This section provides a quick summary of how to troubleshoot the
FK4B. If more information is needed, refer to appropriate 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.
- If motor does not stop running, remove the 7-pin plug from
circuit board. If motor continues to run, replace motor. If motor
stops running, it is either the circuit board or thermostat causing
the problem. Test whether thermostat is at fault by disconnecting
it from the board.
+ CIRCUIT BOARD
- Check 5-amp fuse.
- Check for 230v between terminals M1 and M2. If no voltage
is present, check power to board. 230-v power enters the board
through the black and yellow lead in the 12-pin plug.
- 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-W2. 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.
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.
- Check for 24v between pin-1 and pin-12 on the 16-pin plug.
(See Fig. 19.) If no voltage is present, replace wiring harness. If
voltage is present, jumper screw terminal R-Y/Y2 on circuit board
and check for 24v between pin-12 and pin-14 on 16-pin plug. (See
Fig. 19.) If voltage is present, replace harness.
- If 24v is present, the motor is bad. Replace motor.
Step 8—Accessories
ELECTRONIC AIR CLEANER (EAC)
Familiar 230-vac EAC control/power signal EAC1 and EAC2 is
not available, because the ICM2 blower motor used in the FK4B
Fan Coil is controlled by low-voltage signals. This signal is
replaced by a 24-vdc signal which is provided at circuit board
terminals AUX1 and AUX2. (See Fig 16.)
This signal is present when either G or W is present and is active
in all heating and cooling modes. Because 24-vdc relays may not
be readily available to installer, a kit exists, KFAIR0101ACR,
containing a 24-vdc relay which mounts directly inside EAC
cabinet. User-supplied 110 vac is switched by relay to power air
cleaner when G or W are present. (See Fig. 20 and 21.)
Table 6—FK4B Motor Control Test Values
(With 16-pin connector at motor unplugged)
OPERATING MODE
SCREW TERMINALS
HAVING 24 VAC
** VOLTAGES—7-PIN PLUG P2
W
Pin 1
G
Pin 2
C
Pin 3
C
Pin 4
R
Pin 5
Y/Y2
Pin 6
Y
Pin 7
Electric
Heating
R
W2
W3*
E*
24 vdc
0
0
0
24 vac
0
1-Speed A/C
Cooling
R
Y/Y2
G
0
24 vac
0
0
24 vac
24 vac
0
2-Speed A/C, Low Speed
Cooling
R
Y1
G
0
24 vac
0
0
24 vac
0
24 vac
2-Speed A/C, High Speed
Cooling
R
Y/Y2
G
0
24 vac
0
0
24 vac
24 vac
0
1-Speed HP
Cooling
R
Y/Y2
G
O
0
24 vac
0
0
24 vac
24 vac
0
1-Speed HP
Heating
R
Y/Y2
G
0
24 vac
0
0
24 vac
24 vac
0
2-Speed HP, Low Speed
Cooling
R
Y1
G
O
0
24 vac
0
0
24 vac
0
24 vac
2-Speed HP, Low Speed
Heating
R
Y1
G
0
24 vac
0
0
24 vac
0
24 vac
2-Speed HP, High Speed
Cooling
R
Y/Y2
Y1
G
O
0
24 vac
0
0
24 vac
24 vac
24 vac
2-Speed HP, High Speed
Heating
R
Y/Y2
Y1
G
0
24 vac
0
0
24 vac
24 vac
24 vac
Continuous Fan
R
G
0
24 vac
0
0
24 vac
0
0
* Pin 1 @ 24 vdc with or without jumpers when ever any individual heater input or any combination of heater inputs are energized.
→
** Voltages less than 18 are not recognized on the ICM.
Fig. 19—Wiring Harness 16-Pin Plug
A94375
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
16-PIN PLUG
27