Carrier VECTOR 1800 MT, Operation & Service Manual

Page: 88 / 315

62-11039 4-1
SECTION 4
TEMPERATURE CONTROL
4.1 SYSTEM START--UP
This section describes the unit operation in relation to
temperature control in both diesel and electric standby
operation.
Upon initial start up, when the starting conditions are
met, CSMV and EVXV open to equalize the compressor
discharge and suction pressures so that there is less
than 70 psig (4.8 Bar) difference between them before
the compressor starts.
Once the system is equalized, the CSMV and EVXV will
both close (0% open).
LSV2 & LSV3 will be de--energized (closed)
UL1 & UL2 will be energized (unloaded)
If the unit is in an off cycle and operating in Electric
Standby, the buzzer will come on for 5 seconds prior to
the compressor starting. This does not occur if the unit
is operating in diesel engine mode, and the engine is
already running.
The Speed Solenoid will be de--energized (low speed).
If the engine is not running, it will start now. If the engine
is already running, then it doesn’t have to start again.
The condenser fans turn on.
The compressor starts.
If any compartment is calling for heat, there will be a 10
second delay after the compressor starts and the heater
contactors energize.
The evaporator fan motors will start 10 seconds after the
compressor has started if the suction pressure is lower
than 100 psig (6.8 Bar), or after a maximum of 20
seconds after the compressor starts. Compartment 1
fans will come on first, then Compartment 2, then
Compartment 3, with a 5 second delay between each
compartment.
The compressor will only turn on when the engine is
operating in low speed. When the compressor starts,
the engine will always continue to operate in low speed
for a minimum of 2 minutes before high speed is
allowed.
Whenever the compressor comes on, it will run for a
minimum of 3 minutes. If all compartment temperatures
are satisfied before the 3 minutes are up, the frozen
compartment will continue to operate in cool. If all
compartments have a perishable setpoint, then the
lowest numbered compartment will continue to operate
in cool mode, and the heaters will also come on at the
same time if necessary to maintain the proper
compartment temperature.
MAXIMUM
10 Seconds
Checked at
2 Seconds
VARIABLE
0 to 55 SECONDS
GLOW
CRANK
GLOW
FIRST
ATTEMPT “A”
SECOND
ATTEMPT
THIRD
ATTEMPT
15 Seconds
STOP
REPEAT “A”
+ 5 Seconds
GLOW
1 5 Seconds
STOP
REPEAT “A”
+ 10 Seconds
GLOW
HOMING CSMV
Figure 4--1. Auto Start Sequence