Unloader Control Overrides - Carrier VECTOR 6500 Operation & Service Manual

6. Defrost.
When the unit is in defrost:
S the engine will operate in high speed when heaters
are energized (to supply power for the heaters).
S the engine will operate in low speed when the heat-
ers are de-energized.
7. Door/Remote Switch Configuration.
If the Door/Remote Switch Configuration is set for low
speed, the engine will run in low speed when the
door/remote switch is open/active.
8. Start-Stop Restart.
If the engine is restarted from a Start-Stop off cycle for
any reason except a Start-Stop Parameter Override
Temperature the engine will operate in low speed until all
conditions are met for another off cycle OR for the
Minimum Run Time Functional Parameter value.
9. Low Speed To High Speed Delay.
S The compressor must operate for 2 minutes before
transition to high speed is allowed.
S The time value entered in the High Speed Delay Con-
figuration must be expired before transition to high
speed is allowed.
10.Low Speed Startup.
The time value entered in the Low Speed Startup
Minutes Functional Parameter (for Start-Stop or
Continuous) must be expired before transition to high
speed is allowed.
11. Frozen Set Point/Frozen Set Point Override.
If the set point is a frozen set point (below +10.4°F
[-12°C]) and the temperature is below set point, the
engine will operate in low speed.
12.Low Suction Pressure.
The microprocessor monitors the signal provided by the
Suction Pressure Transducer. If the suction pressure
falls below -2psig (-0.14 bar) for more than 20 seconds,
the engine will operate in low speed for a minimum of 5
minutes, then remain in low speed until the suction
pressure is greater than -2psig (-0.14 bar).
13.Operation With A Perishable Set Point.
If in Start-Stop Operation with a set point in the
perishable range (above +10.4°F [-12°C]) and all
conditions for an OFF Cycle have been met except for
set point, the engine will operate in high speed to pull
down to set point and cycle off quicker.
62-11389
Generally, the unit will go into an off cycle from
high speed when this condition occurs. Howev-
er, if one of the required conditions for shutdown
is no longer met during this time, (for example,
the battery voltage drops below the configured
value, or the charging amps increase above the
configured value, or the engine coolant temper-
ature drops below 122°F (50°C), the engine
may return to low speed operation until the
shutdown condition is satisfied, then shutdown
from low speed.
14.High Speed Pulldown.
If in Continuous Operation with a set point in the
perishable range (above +10.4°F [-12°C]) and the High
Speed Pulldown Configuration is set to YES, the engine
will operate in high speed until the refrigerated
compartment temperature is 0.36°F (0.2°C) above set
point.

4.8.4 Unloader Control Overrides

This section lists the different factors that determine the
operation (de-energizing / loading and energizing / un-
loading) of the unloaders in addition to the unloader con-
trol used in temperature control.
Unloaders operate in priority order for cooling ONLY
(For example: Override 1 supersedes 2 and all lower
overrides.):
The overrides will be allowed in Cargo Protect Mode
only if the override does not use the return or supply
temperature.
There is a minimum delay of 20 seconds between
LOADING and UNLOADING cylinders under all operat-
ing conditions except when the engine is starting.
When the Compressor is Off the Unloaders are always
de-energized.
In all of the following instances UL1 refers to the
Front Unloader and UL2 refers to the Rear Un-
loader.
1. Low Generator Amp Draw.
When the A128 - "LOW/UNBALANCED A/C AMPS"
alarm is activated the compressor will only operate on 2
or 4 cylinders.
2. High Discharge Pressure Or High Generator Amp
Draw.
The microprocessor will not allow additional cylinders to
load whenever the compressor discharge pressure is
above 415 psig (28.3 bar) OR when the compressor
amp draw is within 1 Amp of the maximum allowable
generator current (Maximum Allowable Generator Cur-
rent is a Configuration Setting - Refer to 5.2.1.)
However, if the CDT is above 284°F (140°C) for more
than 30 seconds at the same conditions, loading of one
cylinder bank is allowed.
3. Compressor Restart.
The microprocessor will force the compressor to run in 2
cylinders for 10 minutes when the compressor restarts
4−14
NOTE
NOTE