4-2
T-268-07
4.2 STARTING AND STOPPING INSTRUCTIONS
CAUTION
Make sure that the unit circuit breaker(s)
(CB-1 & CB-2) and the start-stop switch
(ST) are in the OFF position before
connecting to any electrical power source.
a. Starting the Unit
NOTE
The evaporator fans will always start in high
speed regardless of set point and will switch to
low speed after approximately 20 to 30 seconds
if the set point is below --10
_
C (+14
_
F), or
--5
_
C (+23
_
F) optionally.
1. Refer to Pre-Trip Inspection, section 4.1.
2. Check power source for proper voltage. Connect
unit power plug and turn main power ON.
3. Turn refrigeration unit circuit breaker(s), and the
start-stop switch to ON (position “1”).
4.
Units equipped with the integrated DataCORDER:
Trip start is initiated by depressing the ALT.
MODE key and selecting Code dc30, then
depressing the
ENTER
key for five seconds.
5. Refer to section 4.3 after unit is running.
b. Stopping the Unit
Turn the start-stop switch to position “0” (OFF
position).
4.3 AFTER STARTING INSPECTION
a. Check rotation of condenser and evaporator fans.
b. Check compressor oil level. (Refer to section 6.10.)
c. Run unit at least five minutes to stabilize. Start
controller Pre-Trip diagnostics.
(Refer to section 3.2.)
4.4 UNIT OPERATION
4.4.1
Crankcase Heater
When the crankcase heater is installed, it will be
operational whenever the compressor is off and there is
power to the unit. The heater is connected to a set of
normally closed auxiliary contacts on the compressor
contactor (CH).
4.4.2
Probe Check Initiation
Whenever the unit is in normal control mode, that is, not
in pre-trip, defrost or shutdown modes and there are NO
active probe alarms, and alarm codes AL11 and AL12
are inactive (for units so equipped), the following probe
diagnostic functions are performed by the controller.
The following is based on current ML2i operational
software logic, version 5103. Older versions of
software will have differences.
a. Probe Diagnostic Logic
If the unit is configured for standard (Std) “Probe Check
Logic,” the criteria used for comparison between the
primary and secondary
control
probes is:
S
1
_
C (1.8
_
F) for
perishable
set points, above
--10
_
C (+14
_
F), or --5
_
C (+23
_
F) optionally.
S
2
_
C (3.6
_
F) for
frozen
set points, below
above range.
S
If 25 or more of 30 readings taken within a 30
minute period are out-of-range per the above
criteria, then a defrost* is initiated and a
probe check is performed.
b. Special
If the unit is configured for special (SPEC) “Probe
Check Logic,” the above criteria is identical except for
the diagnostic readings which are:
S
If 25 or more of 30 readings taken within a
30 minute period
OR
any 10 consecutive
readings at any time are out-of-range per the
above criteria, then a defrost* is initiated and
a probe check is performed.
* The only time defrost will not be initiated is if the
defrost termination sensor (DTS) is greater than
25.56
_
C (78
_
F).
The 30 minute timer will be reset for each of the
following conditions:
S
At every power up.
S
At the end of every defrost.
S
After every diagnostic check that does not fall
outside of the limits as described under
“standard or special” as outlined above.
