Modes - Carrier 48HC 04-28 Controls, Start-Up, Operation And Troubleshooting

Fan Status Switch (FN.SW)
This configuration identifies if a fan status switch is installed,
and what status (normally open, normally closed) the input is
when the indoor fan is OFF.
Filter Status Switch (FL.SW)
This configuration identifies if a filter status switch is installed,
and what status (normally open, normally closed) the input is
when the filter is CLEAN.
Fire Shutdown Switch (FS.SW)
This configuration identifies if a fire shutdown switch is in-
stalled, and what status (normally open, normally closed) the
input is when the fire or smoke alarm is OFF (no alarm).
Remote Occupancy Switch (RM.SW)
This configuration identifies if a remote occupancy switch is
installed, and what status (normally open, normally closed) the
input is when UNOCCUPIED.
SAT Settling Time (SAT.T)
This configuration sets the settling time of the supply air tem-
perature (SAT). This tells the control how long to wait after a
stage change before trusting the SAT reading. See Adaptive
Thermostat Control (U.CTL = 2, T.CTL = 0) and Space Sensor
Control (U.CTL = 3) within the Cooling operation section for
more information. The factory default value is 240 seconds.
RAT Sensor Installed (RAT.S)
This configuration identifies if a return air temperature (RAT)
sensor is installed. A YES value enables RAT display. A NO
value disables RAT display. Installing an RAT sensor will al-
low economizer differential dry bulb control. Refer to the
economizer operation for more information. RAT sensor is re-
quired for compliance with Title 24 Fault Detection and Diag-
nostics (FDD).
RH Sensor On OAQ Input (RH.S)
This configuration identifies if a space relative humidity sensor
is installed on the outdoor air quality (OAQ) input. A YES val-
ue enables SP.RH display. If a Humdi-MiZer unit, then the unit
determines dehumidification demand based on this input and
the appropriate set point. A NO value disables SP.RH display
and use.
Space Humidity Switch (RH.SW)
This configuration identifies if a space relative humidity switch
is installed on the ENTHALPY input, and what status (normal-
ly open, normally closed) the input is when the space humidity
is HIGH.
Temperature Compensated Start Cooling Factor (TCS.C)
This factor is used in the equation of the Temperature Compensat-
ed Start Time Bias for cooling. A setting of 0 minutes indicates
Temperature Compensated Start in Cooling is not permitted.
Temperature Compensated Start Heating Factor (TCS.H)
This factor is used in the equation of the Temperature Compensat-
ed Start Time Bias for heating. A setting of 0 minutes indicates
Temperature Compensated Start in Heating is not permitted.

Modes

The ComfortLink controls operate under a hierarchy of com-
mand structure as defined by four main elements: the System
Mode, the HVAC Mode, the Occupied status, and the Unit
Control Type.
The System Mode is the top level that defines three main states
of the control system: Disabled, Enabled, or Test.
The HVAC Mode is the next level that defines four main states
of functional operation: Disabled, Fan Only, Cool, and Heat.
The Occupied status affects set points for cooling and heating
in Space Sensor control mode and operation of the economizer
for indoor air quality ventilation and free cooling.
The Unit Control Type (Configuration
fines if temperature control is based on thermostat inputs or
space temperature sensor input.
The general operating mode of the control and the status of
some related operation lockouts are located on the display at
two locations: Run

Modes MODE.
System Mode (SYS)
In Run Status and Operating Modes, the current system mode
is displayed with expandable text. This is an overall state of the
unit.
Three states are: Unit Operation Disabled, Unit Operation En-
abled, or Service Test Enabled.
HVAC Mode (HVAC)
In Run Status and Operating Modes, the current allowed
HVAC mode is displayed with expandable text. This is the
mode the unit decides to run in based on its inputs. There are
four main HVAC modes; cooling has six different expanded
texts. These modes are shown in the following tables.
Fan Mode Expanded Text
HVAC
Disabled Operation
Disabled
Ventilation
Fan Only
(fan-only)
Cooling
Free Cooling
Unoccupied
Free Cooling
Cooling
Reheat1
Reheat2
Reheat1/
Reheat2
Heating Heating
Indoor Fan Mode (F.MOD)
This displays the mode in which the fan is running. There are 8
fan modes in total, the 1-Speed fans can only be in 1 of 2
modes (off or High). Staged Air Volume (SAV) units can uti-
lize all 8 modes if programmed for it. The following table
shows the 8 modes and a brief description for each.
Fan Mode Expanded Text
0 OFF
1 High
2 Low Cool
3 Vent
4 IAQ Override
5 N/A
6 Dehum
7 Low Free Cool
HVAC Operation Disabled (HV.DN)
Allow disabling of HVAC mode. This is only available on a
network connection and shows if the unit has been forced into
the disabled status.
Cool Setpoint In Effect (EFF.C)
This shows the actual setpoint that is being used for control during
cooling mode. If a 0 is displayed, then space sensor control is not
being used and the unit is being controlled by a thermostat.
17
 
UNIT U.CTL) de-

Status MODE and Operating
Brief Description
Unit is in test mode or System mode is
disabled
Fan may run for ventilation
Mechanical cooling
Only economizer used for cooling
Only economizer use for cooling
(occupied cooling set point active)
All running circuits in sub-cooling mode
All running circuits in Hot Gas Reheat
mode
Sub-cooling and Hot Gas Reheat active
Heating mode
Brief Description
When the fan is off
When fan is on in 1-Speed units or at
high speed on SAV units
On SAV units with 2 cooling stages,
when only 1 cooling stage is requested
On SAV units, when in vent mode and
fan is on
On SAV units, in any mode when IAQ
override is active
Not available at this time
On SAV units, in cooling mode, and
specific conditions allow
On SAV units, in cooling mode, and
specific conditions allow