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5126744-UIM-D-1015
16
Johnson Controls Unitary Products
SECTION VI: OPERATION
The following sequences of operation are based on using a single-
stage air conditioning thermostat.
COOLING SEQUENCE OF OPERATION
1.
On a call for cooling, the wall thermostat sends a 24V "Y" signal to
the unit. The unit contactor will close, which energizes the outdoor
fan and the compressor. The 24V signal is also sent to the indoor
blower motor, which will run at the selected cooling speed.
2.
When the demand for cooling has been satisfied, the wall thermo-
stat will remove the 24V "Y" signal from the unit. The contactor will
open and the outdoor fan and the compressor will stop. The indoor
blower has a built-in delay and will continue to run for 60 seconds
after the cooling signal has been removed.
HEATING SEQUENCE OF OPERATION
(for units which have an optional electric heat kit)
1.
On a call for heating, the wall thermostat sends a 24V "W" signal to
the unit. The indoor blower will then start to run at the selected heat-
ing speed. The 24V signal will also go to the sequencer(s) or relays
in the electric heat kit and will turn on the electric heating elements.
2.
When the demand for heating is removed, the wall thermostat will
remove the "W" signal. When the 24V signal is removed from the
electric heat sequencer, the heating elements will turn off. The
indoor blower will continue to run for 60 seconds after the call for
heat is removed.
Electric Heat Limit Switch Operation
When the limit switch opens, the heating elements will turn off. The
indoor blower will continue to run. The limit switch will automatically
reset when the temperature has fallen to a normal level, at which time
the heating elements will be turned on again.
* Motor program has 60 second blower off delay on all 5 speed taps.
Table 13:
Additional Static Resistance
Size (Tons)
CFM
Wet Indoor Coil
Economizer
1
1. The pressure drop through the economizer is greater for 100% outdoor air
than for 100% return air. If the resistance of the return air duct is less than
0.25 IWG, the unit will deliver less CFM during full economizer operation.
2. Filter pressure drop based on standard filter media tested at velocities not
to exceed 300 ft/min.
Filter/Frame Kit
24 (2.0)
500
0.01
0.00
0.01
600
0.01
0.00
0.02
700
0.01
0.00
0.04
800
0.02
0.01
0.06
900
0.03
0.01
0.08
1000
0.04
0.01
0.10
1100
0.05
0.01
0.13
1200
0.06
0.02
0.16
30 (2.5)
700
0.01
0.00
0.04
800
0.02
0.01
0.06
900
0.03
0.01
0.08
1000
0.04
0.01
0.10
1100
0.05
0.01
0.13
1200
0.06
0.02
0.16
1300
0.07
0.03
0.17
36 (3.0)
700
0.01
0.00
0.04
800
0.02
0.01
0.06
900
0.03
0.01
0.08
1000
0.04
0.01
0.10
1100
0.05
0.01
0.13
1200
0.06
0.02
0.16
1300
0.07
0.03
0.17
1400
0.08
0.04
0.18
42 (3.5)
1100
0.02
0.02
0.04
1200
0.03
0.02
0.04
1300
0.04
0.02
0.05
1400
0.05
0.03
0.05
1500
0.06
0.04
0.06
1600
0.07
0.04
0.07
1700
0.07
0.04
0.08
1800
0.08
0.04
0.09
1900
0.09
0.05
0.10
2000
0.09
0.05
0.11
48 (4.0)
1100
0.02
0.02
0.04
1200
0.03
0.02
0.04
1300
0.04
0.02
0.05
1400
0.05
0.03
0.05
1500
0.06
0.04
0.06
1600
0.07
0.04
0.07
1700
0.07
0.04
0.08
1800
0.08
0.04
0.09
1900
0.09
0.05
0.10
2000
0.09
0.05
0.11
60 (5.0)
1100
0.02
0.02
0.04
1200
0.03
0.02
0.04
1300
0.04
0.02
0.05
1400
0.05
0.03
0.05
1500
0.06
0.04
0.06
1600
0.07
0.04
0.07
1700
0.07
0.04
0.08
1800
0.08
0.04
0.09
1900
0.09
0.05
0.10
2000
0.09
0.05
0.11
Table 14:
Thermostat Signals
Signal
State
Function
G
ON
Indoor blower instant on
OFF
Indoor blower off after 60-second delay
W
ON
Indoor blower instant on
Electric heat stages on (if so equipped)
OFF
Electric heat stages off (if so equipped)
Indoor blower off after 60-second delay
G & W
ON
Indoor blower instant on in heating speed
Electric heat stages on (if so equipped)
W OFF
Electric heat stages off (if so equipped)
Indoor blower switches to continuous fan speed
G & Y
ON
Outdoor fan on
Indoor blower instant on in cooling speed
Compressor on
System operates in cooling mode
Y OFF
Compressor instant off
Outdoor fan instant off
Indoor blower switches to continuous fan speed