923178-UTG-B-0114
18
Johnson Controls Unitary Products
Dehumidification Mode
1. Dehumidification Mode Operation
• When T
amb
> T
preset
+ 1.8 °F, cooling and dehumidification
mode will be activated. The compressor and the outdoor
fan will operate while the indoor fan runs at low speed.
• When T
preset
- 3.6 °F
T
amb
T
preset
+ 1.8°F, the compres-
sor remains at its original operation state.
• When T
amb
. < T
preset
- 3.6°F, the compressor will stop, the
outdoor fan will stop after 60 seconds and the indoor fan
will operate at low speed.
2. Protection – Dehumidification Mode
Protection is the same as that under cooling mode section.
Heating Mode
1. Heating Mode Operation
• When T
amb
.
T
preset
+ 3.6°F, heating mode is activated.
The four-way valve, the compressor and the outdoor fan
will operate simultaneously. The indoor fan will run at pre-
set speed defined under “cold air prevention”.
• When T
amb
.
T
preset
+ 9°F, the compressor will stop, the
outdoor fan will stop after 60 seconds, and the indoor fan
will continue to run at low speed for 60 seconds more.
• When T
preset
+ 3.6°F<T
amb
.<T
preset
+ 9°F, the unit will
maintain its original operating status.
In heating mode, the four-way valve is energized and tempera-
ture can be set within a range of 61 - 86°F. The heating symbol
and preset temperature are displayed on the indoor unit display.
2. Defrost Mode Operation
When the system has been running continuously in heating
mode for more than 45 minutes, or an accumulated heating
time of more than 90 minutes, and one of the following condi-
tions are present, the unit will enter defrost mode after 3 min-
utes.
• T
outdoor amb.
≥
41°F, T
outdoor pipe
≤
28.4°F;
• 28.4°F
≤
T
outdoor amb.
• 23°F
≤
T
outdoor amb.
<28.4°F, T
outdoor pipe
≤
17.6°F;
• 14°F
≤
T
outdoor amb.
<23°F, T
outdoor pipe
- T
compensation
≤
(T
out-
door amb
-5.4°F);
• T
outdoor amb.
<14°F, T
outdoor pipe
-T
compensation
≤
(T
outdoor amb.
-
5.4°F)
NOTE:
After defrost mode is energized for the first time, T
compensation
=
0°F. After the first time, T
compensation
is determined by the con-
densing coil temperature T
outdoor pipe
of the last defrost cycle.
• T
outdoor pipe
>35.6°F, T
compensation
= 0°F;
• T
outdoor pipe
≤
35.6°F, T
compensation
= 5.4°F
When in defrost mode the following will occur in the order
described:
a. The indoor fan and compressor stop running
b. The outdoor fan will stop running after 60 seconds.
c. 30seconds later, the four-way valve will close.
d. After 30 seconds, the compressor’s frequency is
increased to defrost frequency.
e. When the compressor has operated in defrost mode for
10 minutes, or T
outdoor pipe
≥
50°F, the compressor will
adjust to 46Hz.
f. After 30 seconds, the compressor will stop.
g. After another 30 seconds, the four-way valve will open.
h. After 60 seconds, the compressor and the outdoor unit fan
will start running. The indoor fan will run under preset cold
air prevention conditions. H1 will be displayed on the
indoor unit display. Defrost frequency is 70Hz.
3. Protection – Heating Mode
• Cold air prevention (Hot Heat Pump) - In heating mode,
after the compressor is energized the indoor fan is delayed
under these conditions to prevent discharging cold air:
When T
indoor amb.
<75°F if:
T
tube
≤
104°F, the indoor fan will not run. The indoor fan
will start running at low speed after 2 minutes.
Within 2 minutes, if T
tube
>104°F, the indoor fan will start
running at low speed.
After 1minute of operation at low speed, the indoor fan
will run at preset speed.
Within 1-minute of low speed operation or 2-minute
non-operation, if T
tube
>108°F, the fan will run at present
speed.
When T
indoor amb.
≥
75°F if:
T
tube
≤
108°F, the indoor fan will run at low speed. After
one minute of operation, the indoor fan will run at pre-
set speed.
Within one-minute of low speed operation, if
T
tube
>104°F, the indoor fan will run at preset speed.
Total current up and frequency down protection occurs:
When I
total
≤
16A, compressor frequency can increase
When I
total
≥
17A, compressor frequency is not allowed
to increase
When I
total
≥
18A, the compressor runs at reduced fre-
quency
When I
total
≥
20A, the compressor stops running and the
outdoor fan stops running after 60 seconds.
Fan Mode
In this mode, the indoor fan will run at preset speed. The com-
pressor, the outdoor fan and the four-way valve will not be run-
ning.
1. In fan mode, temperature can be set within a range of 61 -
86°F.
AUTO Mode
1. AUTO Mode Operation
In AUTO mode, the default cooling setpoint temperature T
preset
is 77°F and the default heating setpoint temperature T
preset
is
68°F. Once activated, the following will occur under these con-
ditions:
• When T
amb.
≤
71.6°F, heating mode is activated.
• When 71.6°F< T
amb.
<78.8°F, fan mode is activated and the
fan icon is displayed on the indoor unit display.
• When T
amb.
≥
78.8°F, cooling mode is activated.
• When T
amb.
≥
T
preset
+1.8°F, the system runs in cooling
mode. The preset temperature is 77°F;
• When T
amb.
≤
T
preset
-1.8°F, the compressor stops running,
the outdoor fan stops running after 1 minute, and the indoor
fan continues to run at a preset speed.
• When T
preset
-1.8°F< T
amb.
< T
preset
+1.8°F, the system con-
tinues to run normally.
• When T
amb.
≤
T
preset
+3.6°F, heating mode is activated.
• T
amb.
≥
T
preset
+9°F, the compressor stops running, the out-
door fan stops running after 1 minute, and the indoor fan
continues to run for about 30 seconds before it stops.
