Non-Adaptive Heating Mode; Cooling Mode; Continuous Blower Mode; Heat Pump Mode - Carrier 58UHV Installation, Start-Up, And Operating Instructions Manual

(1.) When in low-gas heat and thermostat is satisfied,
blower will continue to operate at low-gas heat CFM
until the blower-off delay reaches 90 sec. If blower-off
delay switches (on the 2-stage furnace control) are set
for more than 90 sec, blower will operate at the
selected continuous fan CFM for remaining blower-
off delay time.
(2.) When in high-gas heat and thermostat is satisfied,
blower will continue to operate at high-gas heat CFM
until the blower-off delay expires, for all settings of
the gas heat blower-off delay switches on the 2-stage
furnace control.
i. The furnace control is factory set for a 135-sec blower-off
delay.
2. Non-Adaptive Heating Mode—Two-Stage Thermostat and
2-Stage Heating (See Fig. 14 for thermostat connections).
NOTE: In response to thermostat call for heat R to W/W1 and
with HIGH HEAT ONLY switch SW1 set to OFF, the control
selects low-heat only with LOW HEAT switch SW2 set to ON, or
the control selects adaptive heating mode with LOW HEAT switch
SW2 set to ON. The control selects high-heat only with HIGH-
HEAT ONLY switch SW1 set to ON. In response to thermostat
call for high-gas heat R to W1 and W2, the control selects
high-heat regardless of switch SW1 and SW2 settings. See Tables
6 and 7, and Fig. 15 for description of switch settings or Fig. 16 for
control circuit diagram.
The start-up and shutdown functions and delays described in
item 1 apply to 2-stage heating mode as well, except for
switching from low- to high-gas heat and vice versa.
a. When thermostat calls for heat, the R-W/W1 circuit closes
for low-gas heat or the R to W1-and-W2 circuits close for
high-gas heat. The furnace control performs a self-check,
verifies pressure switch contacts for low- and high-heat
LPS and HPS are normally open, and starts IDM in low
speed or high speed as appropriate.
b. Switching from low- to high-gas heat—If the thermostat
R-W/W1 circuit for low-gas heat is closed and the R-W2
circuit for high-gas heat closes, the control CPU switches
IDM speed from low to high. The HPSR closes. When
IDM provides sufficient pressure to close HPS, high-heat
gas valve solenoid GV is energized. The BLWM switches
to high-stage airflow 5 sec after R-W2 circuit closes.
c. Switching from high- to low-gas heat—If thermostat R-W2
circuit for high-stage opens and R-W/W1 circuit for low-
gas heat remains closed, the control CPU switches IDM
speed from high to low. The HPSR opens to de-energize
high-heat gas valve solenoid GV. When IDM reduces
pressure sufficiently, HPS opens. The low-heat gas valve
solenoid GV remains energized as long as LPS remains
closed. The BLWM switches to low-heat airflow 5 sec after
R-W2 circuit opens.

3. Cooling Mode

a. Single-Speed Cooling Outdoor Unit (See Fig. 13 for
thermostat connections.)
(1.) The thermostat closes R to G-and-Y circuits. The
R-Y circuit starts outdoor unit, and R to G-and-Y/Y2
circuits start the furnace BLWM on cooling speed.
(2.) The EAC terminals are energized with 115v when
BLWM is operating.
(3.) When thermostat is satisfied, the R to G-and-Y cir-
cuits are opened. The outdoor unit stops, and furnace
BLWM continues operating at cooling airflow for an
additional 90 sec.
b. Two-Speed Cooling Outdoor Unit (See Fig. 14 for thermo-
stat connections.)
(1.) The thermostat closes the R to G-and-Y1 circuits for
low cooling or closes the R to G-and-Y1-and-Y/Y2
circuits for high cooling. The R to Y1 circuit operates
the outdoor unit on low-cooling speed. The R to
G-and-Y1 circuit operates the furnace BLWM at
low-cooling airflow (65 percent of single-speed cool-
ing airflow; different airflow than for low-gas heat).
The R to Y1-and-Y2 circuits operate the outdoor unit
on high-cooling airflow, and the R to G-and-Y/Y2-
and-Y1 circuits operate furnace BLWM at high-
cooling airflow. Two-speed high-cooling airflow is
105 percent of single-speed cooling airflow.
NOTE: Y1 is found in the furnace and in the outdoor unit. The
furnace control CPU controls BLWM airflow by sensing only
G-and-Y1 for low-cooling airflow and G-and-Y1-and-Y/Y2 for
high-cooling airflow.
(2.) Terminals EAC-1 and EAC-2 are energized with 115v
when the BLWM is operating on either cooling
airflow.
(3.) When the thermostat is satisfied, the R to G-and-Y1
or R to G-and-Y1-and-Y/Y2 circuits open. The out-
door unit stops, the furnace blower continues operat-
ing on same cooling airflow for an additional 90 sec.
4. Continuous-Blower Mode
a. When R to G circuit is closed by the thermostat, BLWM
operates at LOW, MED, or HI (50 percent, 65 percent, or
100 percent of single-speed cooling airflow; different than
low-gas heat airflow). LOW, MED, and HI selections are
described in Set-up Procedures. Terminals EAC-1 and
EAC-2 are energized with 115v as long as the BLWM is
operating.
b. During a call for heat, the BLWM stops during igniter
warm-up (17 sec), ignition (7 sec), and blower-on delay (45
sec), allowing the furnace heat exchangers to heat up
quickly, after which the BLWM operates at the appropriate
gas heating airflow.
c. The BLWM reverts to continuous blower airflow after the
heating cycle is completed. In high-gas heat, the furnace
control CPU and ICM2+ motor control hold the BLWM at
low-heat airflow for a 90-sec blower-off delay period
(regardless of selected blower-off delay) before reverting to
continuous-blower airflow.
d. When thermostat "calls for low-cooling," the BLWM
switches to low-cool airflow or the selected continuous-
blower airflow, whichever is greater. Note that a HI
selection for continuous-blower airflow will provide more
than normal airflow during 2-speed low-cooling. When the
thermostat is satisfied, the BLWM switches to continuous-
blower airflow.
e. When the thermostat calls for high cooling, the BLWM
operates at high-cool airflow. When the thermostat is
satisfied, BLWM operates an additional 2 sec at high-cool
airflow before reverting back to continuous-blower airflow.
f. When R-G circuit is opened, BLWM continues operating
for an additional 90 sec, if no other function requires
BLWM operation.

5. Heat Pump Mode

NOTE: A dual-fuel thermostat is required with single-speed heat
pumps. See dual-fuel thermostat Installation Instructions for
single-speed heat pump thermostat connections. No interface kit is
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