Space Temperature Control Mode Response For C.typ=3; C.typ=4 (Tstat 2 Stg) Required Configuration - Carrier 38APS025 Manual

On power up or changing from Off to Enabled, the machine
will remain off until Minutes Off Time (Configuration
OPT2 DELY) timer has expired. See Minutes Off Time on
page 128 for additional information. Liquid line solenoid valve
operation is as described in Liquid Line Solenoid Valves on
page 40. Time Guard is honored for all compressors. For spe-
cific information on Time Guard, see MDTG - Time Guard
Active on page 135.
In this Control Type, Space Temp Control Mode, Run Sta-
tus VIEW SPT.M=0 (Off Cool) as long as Control Mode
Run Status VIEW STAT=1 (Off Local), 2 (Off CCN), 3
(Off Time), 4 (Off Emrgcy), or 9 (SPT Satisfied). When the
Control Mode STAT=5 (On Local), 6 (On CCN), or 7 (On
Time), SPT.M=1 (Lo Cool) if Y1 is closed, Inputs
GEN.I Y.1=ON or SPT.M=2 (High Cool) if Y2 is closed,
Inputs GEN.I Y.2=ON. If Y1 and Y2 are both open,
Y.1=OFF and Y.2=OFF, STAT=9 (SPT Satisfied) and
SPT.M=0 (Off Cool) will be displayed. In this Control Type, if
the Indoor Fan Status Switch opens (Inputs GEN.I
ID.F.A=OFF), Control Mode (STAT) will change to 8 (IDFS
Not On) as long as there is no call for cooling, Y.1=OFF and
Y.2=OFF. If there is a call for cooling, Y.1=ON or Y.2=ON the
unit will alarm and STAT switch to 4 (Off Emrgcy). Table 28
shows the space temperature control mode response for
C.TYP=3.
Table 28 — Space Temperature Control Mode
Response for C.TYP=3
Y1
CONTROL
STATUS STATUS
MODE STAT
Y.1
1 (Off Local) Off or On Off or On
2 (Off CCN) Off or On Off or On
3 (Off Time) Off or On Off or On
4 (Off Emrgcy) Off or On Off or On
On
5 (On Local)
Off or On
On
6 (On CCN)
Off or On
On
7 (On Time)
Off or On
8
Off or On Off or On
(IDFS Not On)
9
Off
(SPT Satisfied)
38APD — On a call for cooling, the Indoor Fan Status Cir A,
(Inputs GEN.I ID.F.A) is checked. The switch must be
closed before the capacity routine will start. The lead circuit is
determined. See Lead/Lag Determination on page 112. The
lead compressor will be determined and started. See Circuit
Compressor Staging on page 112. If the lead compressor is a
digital compressor and is enabled, the compressor will start ful-
ly loaded for 90 seconds prior to starting to cycle between load-
ed and unloaded. Compressors will be staged until the unit's
capacity meets the Control Point (CTPT) as described in Sup-
ply Air Temperature Control on page 110. If additional capaci-
ty requires the lag circuit to start, the lag circuit's lead compres-
sor will be determined and started. During operation, the con-
trols will stage the condenser fans to maintain head pressure.
See Head Pressure Control on page 117.
As part of normal operation, if a single compressor in a mul-
tiple compressor circuit (38APD040-130) operates for the cu-
mulative time of 60 minutes without an increase in circuit ca-
pacity, an oil recovery routine is initiated. When this routine is
initiated, a second compressor in the circuit is started. Once
started, the normal capacity control routine takes priority and
will turn off the compressor if needed.
SPACE
INDOOR
TEMPER-
Y2 FAN
ATURE
STATUS
CONTROL
Y.2 CIR A
MODE
ID.F.A
SPT.M
Off or On 0 (Off Cool)
Off or On 0 (Off Cool)
Off or On 0 (Off Cool)
Off or On 0 (Off Cool)
Off On 1 (Lo Cool)
On On 2 (Hi Cool)
Off On 1 (Lo Cool)
On On 2 (Hi Cool)
Off On 1 (Lo Cool)
On On 2 (Hi Cool)
Off 0 (Cool Off)
Off On 0 (Cool Off)
As the capacity requirement begins to decrease, the ma-
chine controls will reduce the unit's capacity to maintain the
Control Point. If the unit is equipped with Minimum Load
Control, it will not be active until the unit is on its last stage of
capacity.
38APS Units — On a call for cooling, the Indoor Fan Status
Cir A (Inputs GEN.I ID.F.A) is checked. The switch must
be closed before the capacity routine will start. The lead com-
pressor will be determined and started. See Circuit Compressor
Staging on page 112. If the lead compressor is a digital com-
pressor and is enabled, the compressor will start fully loaded
for 90 seconds prior to starting to cycle between loaded and un-
loaded. Compressors will be staged until the unit's capacity
meets the Control Point (CTPT) as described in Supply Air
Temperature Control on page 110. During operation, the con-
trols will stage the condenser fans to maintain head pressure.
See Head Pressure Control on page 117.
As part of normal operation, if a single compressor operates
for the cumulative time of 60 minutes without an increase in
circuit capacity, an oil recovery routine is initiated. When this
routine is initiated, a second compressor in the circuit is started.
Once started, the normal capacity control routine takes priority
and will turn off the compressor if needed.
As the capacity requirement begins to decrease, the ma-
chine controls will reduce the unit's capacity to maintain the
Control Point. If the unit is equipped with Minimum Load
Control, it will not be active until the unit is on its last stage of
capacity.
C.TYP = 4 (TSTAT 2 STG) — This configuration allows
the MBB to monitor the thermostat inputs to make capacity
stage decisions. If Y1 input is closed, no more than 50% of the
circuit capacity will be energized. If Y2 is closed, 100% of the
circuit capacity will be energized for that circuit and air han-
dler. Y1 closure is not required for 100% capacity.
Recommended Applications — This control type is recom-
mended for constant volume, non-digital compressor applica-
tions with units with less than 3 stages of compression. It is not
recommended for units with more than two stages of capacity.
This control scheme cannot be used with:
• Units with digital compressors. Digital operation is not
supported with this control scheme.
• Minimum Load Control is not supported with this con-
trol scheme.
Hardware Requirements
• 2-stage thermostat
Required Configurations — Table 29 lists the configurations
required for proper operation.
Wiring — See Fig. 82.
Table 29 — C.TYP=4 (Tstat 2 Stg) Required
CONFIGURATION MODE
SUBMODE ITEM DISPLAY
OPT2 C.TYP
69
Configuration
ITEM
COMMENT
DESCRIPTION
Default: 4
Machine Con- Range: 1 to 9
X
trol Type Set item to 4
(Tstat 2 Stg)