Defrost Mode; Set-Up Procedures - Carrier 58UHV Installation, Start-Up, And Operating Instructions Manual

needed for 2-speed heat pumps. See 2-speed heat pump Installation
Instructions to determine whether a standard or dual-fuel heat
pump thermostat is required and for thermostat connections.
a. Single-Speed Heat Pump Cooling
(1.) The thermostat and interface kit close the R to
Y/Y2-and-G-and-O circuits to operate the furnace
BLWM at cooling airflow. The Y/Y2 input to the
furnace control is necessary to provide adequate cool-
ing airflow.
(2.) Terminals EAC-1 and EAC-2 are energized with 115v
when BLWM is operating.
(3.) When thermostat is satisfied, furnace BLWM contin-
ues operating at cooling airflow for an additional 90
sec.
b. Two-Speed Heat Pump Cooling
(1.) The thermostat R to G-and-Y1-and-O circuits operate
the furnace BLWM at low-cool airflow. The thermo-
stat R to G-and-Y/Y2-and-Y1-and-O circuits operate
the furnace BLWM at high-cool airflow (105 percent
of single-speed cooling airflow).
NOTE: The furnace control CPU controls blower airflow by
sensing G, Y1, and O for low-cool airflow and G, Y1, Y/Y2, and
O for 2-speed high-cool airflow.
(2.) Terminals EAC-1 and EAC-2 are energized with 115v
when the BLWM is operating at either cooling air-
flow.
(3.) When the thermostat is satisfied, the furnace BLWM
continues operating at the same cooling airflow for an
additional 90 sec.
c. Single-Speed Heat Pump Heating
(1.) The thermostat and accessory interface kit R to G-
and-Y/Y2 circuits operate the furnace BLWM at heat
pump heating airflow. Heating airflow is the same as
cooling airflow for airflow selection HP-EFFY and 90
percent of cooling airflow for HP-CMFT selection.
(2.) Terminals EAC-1 and EAC-2 are energized with 115v
when the BLWM is operating.
(3.) When thermostat is satisfied, the furnace BLWM
continues operating at same heat pump heating airflow
for an additional 90 sec.
d. Two-Speed Heat Pump Heating
(1.) The thermostat closes R to Y1-and-G circuits for low
heat and operates the furnace BLWM at heat pump
low-heat airflow (may not be identical to low-cooling
airflow, depending on HP selection at airflow selec-
tor). Closing R-Y/Y2, Y1 and G circuits to furnace
provides BLWM heat pump high-heat airflow.
NOTE: The furnace control CPU controls BLWM airflow by
sensing G and Y1 for heat pump low-heat airflow, and G, Y1, and
Y/Y2 for heat pump high-heat airflow (105 percent of single-speed
heating airflow).
(2.) Terminals EAC-1 and EAC-2 are energized with 115v
when BLWM is operating at either heating airflow.
(3.) When the thermostat is satisfied, the furnace BLWM
continues operating at same heating airflow for an
additional 90 sec.
(4.) Opening only R-Y/Y2 circuit switches BLWM to heat
pump low-heat airflow.
6. Defrost
a. When furnace control R to W/W1-and-Y/Y2 circuits are
closed, furnace control CPU continues BLWM operation at
heat pump heating airflow until the end of prepurge period,
then shuts off until the end of HSI igniter-on period (22
sec).
b. When installed with a heat pump, the furnace control CPU
automatically holds the blower-off time to 22 sec during
HSI igniter-on period. After 17 sec of the HSI igniter-on
period, a trial-for-ignition sequence occurs as described
above for gas heating. After flame is proven and without a
blower-on delay, BLWM then operates at high-gas-heat
airflow during defrost. For both single-speed and 2-speed
heat pumps, defrost mode is in high-gas heat only.
c. When furnace control R-W/W1 circuit is opened, the
furnace control CPU begins the normal inducer post-purge
period and the BLWM continues operating for the blower-
off delay period. If the R-G circuit remains closed, the
BLWM reverts to continuous-blower operation.

SET-UP PROCEDURES

The ICM2+ blower motor operating mode selections are made on
the airflow selector (AFS) control with color-coded jumper wires.
The factory jumper settings have large bold circles marked around
the pins. (See Fig. 17.)
NOTE: The ICM2+ furnaces are not approved for twinning.
1. Gas Heating
a. The VIOLET wire is factory connected to 1 of 4 pins: A, B,
C, or D on airflow selector. The factory pin selection can be
checked by noting PIN marking in lower right-hand corner
of furnace rating plate.
b. The gas heating air temperature rise is selected on airflow
selector (See Figs. 16 and 17.) with RED and VIOLET
jumper wires. The selections are MID, HI, and MED-HI.
MID gives mid point of temperature rise range marked on
rating plate. HI gives high end of temperature rise range.
MID-HI gives temperature rise about halfway between
MID and HI. Select the rise by moving WHITE connectors
on RED and VIOLET jumper wires to desired pin posi-
tions. These settings select the rise for high and low heat.
See Table 8 for air temperature rise.
2. Cooling and Heat Pump Heating
a. The cooling and heat pump selections can be determined
from Tables 9 and 10. The selections are made by moving
the WHITE connector on appropriately colored jumper
wire to desired pin position.
NOTE: Power must be cycled off and then on for the cool size
selection to take effect. Power need not be cycled off and on for the
CFM/TON to take effect.
b. The YELLOW COOL SIZE jumper is used to select
airflow to match the needed tons for the cooling or heat
pump system. The BLUE CFM/TON jumper is used to
select a slight adjustment to airflow. The traditional CFM
per ton is 400 for cooling and heat pump airflow. 350 CFM
per ton is the airflow used to attain best efficiency with
these units. 315 CFM per ton is the airflow used for
improved dehumidification and/or with undersized ducts.
Additional humidity control can be attained by using a
humidistat. (See Set-up Procedures section, item 4.)
c. The ORANGE jumper wire selects airflow for cooling-only
(AC) or heat pump heating and cooling, and selects heat
pump heating best efficiency (HP EFFY) or enhanced
comfort (HP CMFT). HP EFFY provides the same heating
16