Controls Operation; Modes - Carrier Weathermaster 48P030-100 Controls, Start-Up, Operation, Service, And Troubleshooting

CONTROLS OPERATION

Modes

The ComfortLink controls operate under a hierarchy of command
structure as defined by three essential elements: the System mode,
the HVAC mode, and the Control mode. The System mode is the
top level mode that defines three essential states for the control
system: OFF, RUN and TEST.
The HVAC mode is the functional level underneath the System
mode which further defines the operation of the control.
The Control mode is essentially the control type of the unit
 
(Configuration UNIT C.TYP). This defines where the con-
trol looks to establish a cooling or heating mode. Furthermore,
there are a number of modes which operate concurrently when
the unit is running. The operating modes of the control are locat-
ed at the local displays under Operating Modes. See Table 31.
Currently Occupied (OCC)
This variable displays the current occupancy state of the unit.
Timed Override in Effect (T.OVR)
This variable displays if the state of occupancy is currently occu-
pied due to an override.
DCV Resetting Minimum Position (DCV)
This variable displays if the economizer position has been lowered
from its maximum vent position due to demand-controlled
ventilation.
Supply Air Reset (SA.R)
This variable displays if the supply air set point that the rooftop is
attempting to maintain is currently being reset upwards. This ap-
plies to cooling only.
Table 31 — Operating Modes Display Table
ITEM EXPANSION
SYS.M ascii string
HVAC ascii string
CTRL ascii string
MODE MODES CONTROLLING UNIT
OCC Currently Occupied
T.OVR Timed Override in Effect
DCV DCV Resetting Min Pos
SA.R Supply Air Reset
DMD.L Demand Limit in Effect
T.C.ST Temp.Compensated Start
IAQ.P IAQ Pre-Occ Purge Active
LINK Linkage Active — CCN
LOCK Mech.Cooling Locked Out
H.NUM HVAC Mode Numerical Form
Demand Limit in Effect (DMD.L)
This variable displays if the mechanical cooling capacity is cur-
rently being limited or reduced by a third party.
Temperature Compensated Start (T.C.ST)
This variable displays if Heating or Cooling has been initiated be-
fore occupancy to pre-condition the space.
IAQ Pre-Occupancy Purge Active (IAQ.P)
This variable displays if the economizer is open and the fan is on
to pre-ventilate the building before occupancy.
Linkage Active CCN (LINK)
This variable displays if a linkage master in a zoning system has
established "linkage" with this air source (rooftop).
Mechanical Cooling Locked Out (LOCK)
This variable displays if mechanical cooling is currently being
locked out due to low outside air temperature.
HVAC Mode Numerical Form (H.NUM)
This is a numerical representation of the HVAC modes which may
be read via a point read.
RANGE CCN POINT
— n/a
— n/a
— n/a
ON/OFF MODEOCCP
ON/OFF MODETOVR
ON/OFF MODEADCV
ON/OFF MODESARS
ON/OFF MODEDMLT
ON/OFF MODETCST
ON/OFF MODEIQPG
ON/OFF MODELINK
ON/OFF MODELOCK
number MODEHVAC
44
SYSTEM MODES (OPERATING MODES
System Mode Off
When the system mode is OFF, all outputs are to be shut down and
no machine control is possible. The following list displays the text
assigned to the System Mode when in the OFF mode and the con-
ditions that may cause this mode are checked in the following hi-
erarchal order:
1. Wake up timer
("Initializing System ...")
2. System in the process of shutting down compressors and
waiting for timeguards to expire.
3. ("Shutting Down ...")
4. Factory shut down (internal factory control level —
SHUTDOWN).
("Factory Shut Down")
5. Unit Stop (software application level variable that acts as a
hard shut down
("Local Machine Stop")
6. Fire Shut Down (fire shutdown condition based on the Fire
Shutdown Input
("Fire-Shutdown Mode")
7. Emergency Stop, which is forced over the CCN through
the Emergency
("CCN Emergency Stop")
8. Start-up
("Startup Delay = 0-900 secs")
9. Service test
("Service Test Ending")
10. Unexplained internal
("Internal Failure")
System Mode Test
When the system mode is Test, the control is limited to the Test
mode and is controllable via the local displays (scrolling mar-
quee and Navigator™ display). The System Test modes are Fac-
tory Test Enabled and Service Test Enabled. See the Service Test
section on page 38 for details on test control in this mode.
1. Factory Test mode ("Factory test enabled")
2. Service Test mode ("Service test enabled")
System Mode Run
When the system mode is Run, the software application in the
control is free to run the HVAC control routines by which cooling,
heating, IAQ, etc., is possible. There are two possible text displays
for this mode: one is normal run mode and the other occurs if one
of the following fire-smoke modes is present: smoke purge, pres-
surization or evacuation.
1. Normal run time state ("Unit Operation Enabled")
2. Fire-Smoke control mode ("Fire-Smoke Control")
HVAC MODES (OPERATING MODE
The HVAC mode is dependent on the system mode to allow it to
further determine the operational state of the rooftop unit. The ac-
tual determination of an HVAC mode is based on a hierarchal de-
cision making process whereby certain overrides may interfere
with normal temperature/humidity control. The decision making
process that determines the HVAC mode is shown in Fig. 3 and
Appendix E.
Each HVAC mode is described below. The HVAC mode number
is shown in the parentheses after the mode.
HVAC Mode — STARTING UP (0)
The unit is transitioning from the OFF mode to a different mode.
HVAC Mode — DISABLED (1)
The unit is shut down due to a software disable command through
the scrolling marquee, a CCN emergency stop command, a ser-
vice test end, or a control-type change delay.
HVAC Mode — SHUTTING DOWN (2)
The unit is transitioning from a mode to the OFF mode.

SYS.M)
on a power

— Service Test STOP).
 
(Inputs FIRE
Stop Variable (EMSTOP).
ending transition
software

HVAC)
reset.
FSD).
Delay.
timer.
failure.