Selecting Basic Heating Airflow; Selecting Basic Cooling / Heat Pump Airflow; Dehumidification Options; Unit Maintenance - Maytag B6BM series Installation Instructions Manual

(see page 11). During normal operation, the motor will
gradually change speeds during start-up, shut down, when
thermostat inputs change, and when the duct static pressure
changes (vents closed or opened, filter clogging, etc.). The
air handler is configured by setting the selector switches and
removing jumper connectors.

Selecting Basic Heating Airflow

Fixed & variable speed motor control boards
23) & Figure 17) contain a set of dip switches for setting
the blower speed. For B6EM models, pins 1-4 set the speed
for heating. For B6VM models, the A/B switch must be set
for the appropriate cabinet size (either setting can be used
for C-size cabinets). The airflow is set automatically based
on the amount of installed heat. For both B6EM & B6VM
models, the cooling speed is selected via switches 5,6,7,&
8. To determine the appropriate switch settings for your
installation, see Table 6, (page
Table 8, (page 21), or Table 9, (page

Selecting Basic Cooling / Heat Pump Airflow

The basic cooling/heat-pump airflow is controlled by setting
switches 5 - 8 on the motor control board (mounted on the
blower). All airflows for other modes of operation (except
electric heat) are determined by this basic setting. FAN ONLY
would deliver 50% of the selected cooling airflow.
(page 21) lists the basic airflow values versus the airflow
selector switch settings and ranges of basic air flow settings
recommended for each nominal system capacity.
• When operating in the heat pump mode, a higher basic
airflow setting will increase the energy efficiency and
capacity but will also decrease the supply air temperature.
• For maximum capacity and energy efficiency, select an
airflow at or near the top of the range for that nominal
capacity. See Table 8, (page
• For maximum dehumidification, select an airflow near the
middle or bottom of the range for that nominal capacity.
Additional information on humidity control can be found
in the Humidistat and Delay Setting sections.
• For thermostats with a dehumidifier output, use a field
supplied wire to connect the thermostat's dehumidifier
output to the terminal marked DHuM. The thermostat
should be set so that the DHuM output should be high
(energized) when dehumidification is needed. See also
Dehumidification Options section.
IMPoRtANt! If coil icing is observed, the basic cooling/
heat-pump airflow selected may be too low. Verify the setting
selected is within the range shown in
system is properly charged. Please refer to the instructions
supplied with the outdoor unit. If icing continues to occur,
raise the selected airflow one or two steps.
NotE: Variable speed air handlers with SEER ratings higher
than 15 are matched with a 2-stage cooling outdoor unit.
They are programmed to operate at 75% of the selected
airflow while the system is in the lo-cool mode and 100% of
the selected airflow while in hi-cool mode.

Dehumidification options

(B6EM or B6VM Models Only)
Both motor control boards
17 (page 24) have a DHuM connection that allows the
system to increase the amount of humidity that is removed
from the circulating air. This is accomplished by reducing the
CFM and allowing the cooling coil to become colder. There
are many ways that this can be electrically wired.
(Figure 16 (page
20), Table 7, (page
22).
Table 8,
21).
Table 8 and that the the
Figure 16 (page 23) & Figure
1. If the room thermostat incorporates a humidity sensor and
DHuM output, connect the DHuM on the thermostat to
the DHuM terminal on the motor control board.
2. If using a separate humidistat, connect the DHuM & R
terminals on the humidistat to the DHuM & R terminals on
the motor control board of the air handler. In this option, the
DHuM output of the humidistat must be set to be normally
open and closed when there is a call for humidification.
See Figure 11.
3. For cooling only system: If a humidistat is not available, it is
an acceptable option to connect the R & DHuM terminals
on the motor control board together with a field supplied
wire. This option causes the blower to run at a reduced
CFM for 10 minutes after a call for cooling. NotE: Heat
pump systems must use a thermostat with humidity sensor
or separate humidistat to prevent blower speed reduction
in heat mode.
21),
HUMIDISTAT
DHUM
R
Figure 12.

uNIt MAINtENANcE

Proper maintenance is most important to achieve the best
performance from a air handler. Some of the components
and their locations are shown in
any component of the air handler must be replaced, use
only factory authorized replacement parts specified in the
Replacement Parts List provided online.
ELEctRIcAL SHocK, FIRE oR
EXPLoSIoN HAZARD
Failure to follow safety warnings exactly could
result in serious injury or property damage.
Improper servicing could result in dangerous
operation, serious injury, death or property
damage.
• Before servicing,disconnect all electrical power
to the indoor blower.
• When servicing controls, label all wires prior
to disconnecting. Reconnect wires correctly.
• Verify proper operation after servicing.
• These maintenance instructions are primarily intended
to assist qualified technicians experienced in the proper
maintenance and operation of this appliance.
• Always reinstall the doors on the air handler after servicing
or cleaning/changing the filters. Do not operate the air
handler without all doors and covers in place.
• Verify that the thermostat is properly installed and is
not being affected by drafts or heat from lamps or other
appliances.
• To achieve the best performance and minimize equipment
failure, it is recommended that a yearly maintenance
checkup be performed. At a minimum, this check should
include the following items:
MOTOR
CONTROL BOARD
DHUM
R
DHuM wiring configuration
Figure 13 (page
wARNING:
17). If
15