Service Manual

SERVICE AND MAINTENANCE FAN COILS
496 08 8001 02 5
Specifications subject to change without notice.
FEM4P, FEM4X, FEA4X, FXM4, WAHA, WAPM,
WAPT, WAPL, WAHM, WAHT, WAHL, WAXM,
WAXT, WAXL, REM4P, REM4X
MULTI−SPEED ECM FAN MOTOR
The multi−speed ECM motor used with this product contains
two parts: the control module and the motor winding section.
Do not assume the motor or module is defective if it will not
start. Go through the steps described below before replacing
control module or entire motor. The control module is available
as a replacement part.
A. It is normal for the motor to rock back and forth on startup.
Do not replace the motor if this is the only problem
identified.
B. If the motor is not running:
1. Check for proper high voltage and ground at the L,G,
and N connections at the motor. Correct any voltage
issue before proceeding to the next step.
2. The motor is communicated through 24−Vac signals to
the 1,2,3,4,5 and C (common) terminals. Not all taps are
programmed, if low voltage is applied to an
non−programmed terminal, the motor will not operate,
which is normal. Verify the part number of the motor
matches the correct replacement motor part number for
the unit model number.
3. Initiate a demand from the thermostat and check the
voltage between C (common) and terminal 1− 5. If
voltage is present and the motor isn’t operating, then the
motor/control module is failed.
C. Prior to installing the replacement control module, the
motor section condition needs to be verified.
1. Check to see if the blower wheel spins freely.
2. To check for short to ground, use an ohmmeter to
measure the resistance from any one of the motor
connector pins to the aluminum end plate of the motor.
This resistance should be greater than 100,000 ohms.
3. Check the motor phase−to−phase resistance between
each of the leads in the three−pin motor connector. The
lead−to−lead resistance across any two leads should be
less than 20 ohms. Each lead−to−lead resistance
should be the same within −/+ 10 percent.
4. ATTENTION: If any motor fails any of the three tests, do
not install a new control module. The new control can
fail if placed on a defective motor.
The prior fan coil models with multi−speed ECM blower motors
used a printed circuit board, similar to the PSC models. The
current fan coils do not use the printed circuit board and rely
on the motor control programming to provide the off−delay
timing.
Another design aspect of the control board was to provide a
resistor in the “G” circuit in case a power stealing thermostat
was used. This resistor is no part of the wiring harness, as
shown on wiring diagram. The resistor is a 2−watt, 1500−ohm
resistor.
If the resistor has failed open, a likely cause is due to the
power stealing thermostat. Connecting C (common) may
resolve the issue. Having an open resistor should not affect
the operation of the motor.
Fan Speed Selection
The fan speed selection is done at the motor connector. Units
with or without electric heaters require a minimum CFM. Refer
to the unit wiring label to ensure that the fan speed selected is
not lower than the minimum fan speed indicated.
To change motor speeds disconnect the BLUE fan lead from
motor connector terminal No. 2 (factory default position) and
move to desired speed-tap; 1, 2, 3, or 5.
Speed-taps 1, 2, and 3 have a 90−second blower off time
delay pre-programmed into the motor. Speed-tap 4 is used for
electric heat only (with 0 second blower time delay) and the
WHITE wire should remain on tap 4. Speed-tap 5 is used for
high static applications, but has a 0−
second blower time delay
pre-programmed into the motor. See Airflow Performance
tables for actual CFM. Also, see Figure 3 for motor speed
selection location.
NOTE: In low static applications, lower motor speed tap
should be used to reduce possibility of water being blown off
coil.
Tap 1 Low 90 sec off delay
Tap 2 Medium 90 sec off delay
Tap 3 High 90 sec off delay
Tap 4 Electric heat † 0 sec off delay
Tap 5 Max ‡ 0 sec off delay
† electric heat airflow is same CFM as Tap 3, except 0 sec off delay
‡ high static applications, see airflow tables for max airflow
Figure 3 − Motor Speed Selection
1 2 3 4 5
Speed Taps may be located on motor,
or on plug close to motor.
CLGN
1 2 3 4 5
TWO MOTOR STYLES
A11048