Modes; General Operation - Carrier 48LC 04 Controls, Start-Up, Operation And Troubleshooting

Temperature Compensated Start Cooling Factor
(TCS.C)
This factor is used in the equation of the Temperature Compensated
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
Compensated 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 command
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UNITU.CTL) defines
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 Status MODE and Operating 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 Enabled,
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 below.
HVAC
Expanded Text
Mode
Disabled HVAC Operation Unit is in test mode or System mode is dis-
Disabled abled
Fan Ventilation Fan may run for ventilation
Only (fan--- only)
Cooling Cooling Mechanical cooling
Free Cooling Only economizer used for cooling
Unoccupied Only economizer use for cooling (occupied
Free Cooling cooling set point active)
Dehumidification Running advanced dehumidification
Dehum Cooling Running cooling with advanced dehumidification
Heating Heating Heating mode
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 utilize all 8 modes if
programmed for it. The table below shows the 8 modes and a brief
description for each.
Fan
Expanded Text
Mode
0 OFF When the fan is off
1 Speed 1 Pre--- Low Speed
2 Speed 2 Low Speed
3 Speed 3 Pre--- High Speed
4 Max Speed When running at Maximum Fan Speed
5 Vent When in Ventilation mode and the fan is on
Brief Description
Brief Description
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.
Heat Setpoint In Effect (EFF.H)
This shows the actual setpoint that is being used for control during
heating mode. If a 0 is displayed, then space sensor control is not
being used and the unit is being controlled by a thermostat.
Currently Occupied (OCC)
Displays the current state of assumed space occupancy based on
unit configuration and inputs.
Timed Override in Effect (T.OVR)
Displays if the state of occupancy is currently occupied due to an
override.
Linkage Active (LINK)
Displays if a linkage communication "Linkage" is established
between the unit and a linkage source.
Demand Limit in Effect (D.LMT)
Displays if a demand limit has been placed on the unit's capacity.
Compressor OAT Lockout (C.LOC)
Displays if operation of the compressor is prevented due to outdoor
temperature limit lockout.
Heat OAT Lockout (H.LOC)
Displays if heating operation is prevented due to outdoor
temperature limit lockout.
Econo Cool OAT Lockout (E.LOC)
Displays if economizer operation for cooling is prevented due to
outdoor temperature limit lockout.

General Operation

48/50LC units can provide cooling, dehumidification, heating, and
ventilation operation. Each unit will operate under one of two
basic types of control: thermostat or space temperature sensor.
There are many inputs, configurations, safety factors, and
conditions that ultimately control the unit. Refer to the specific
operation sections for detail on a specific unit operation.
When thermostat control is enabled (ConfigurationUNIT
U.CTL = 1), the unit will operate based on discrete input
commands (G, Y1, Y2, W1, and W2) and there is a one minute
time delay between modes and when re- -entering a mode. The G
command calls for ventilation, the Y1 and Y2 commands call for
cooling, and the W1 and W2 commands call for heating.
Thermostat Control Type (ConfigurationUNITT.CTL) affects
how cooling operates based on Y1 and Y2 commands and if
cooling/heating stage time guards are applied.
When space temperature sensor control is enabled (Configuration
UNITU.CTL = 2), the unit will try to maintain the Space
Temperature (TemperaturesAIR.TSPT) between the effective
cool and heat setpoints (Run StatusMODEEFF.C and
EFF.H). However, to minimize unnecessary cool to heat and heat
to cool changes, there is a 10 minute delay after the last stage turns
off before the control will switch modes and a 1 minute delay when
re- -entering the last mode. Linkage operation overrides the mode
changeover delay to 15 seconds. The cooling and heating Mode
Select Timeguard (Operating ModesCOOLMS.TG and
Operating ModesHEATMS.TG) show the remaining time
before allowing the respective mode to be entered.
13