Thermo King 920000, Manual

Page: 53 / 190

Operating Instructions
53
6. Set each thermostat setpoint at the required
temperature. Do not set a thermostat lower
than necessary. Setting the thermostat below
the required setpoint will not make the unit
cool faster.
7. If a thermostat is demanding Cool or Heat, the
electric motor will start and the unit will
operate. The unit will not operate if the box
temperature is near the thermostat setpoint.
8. Check the fan rotation by holding a small
piece of cloth or paper in front of the
condenser grille. Correct fan rotation will
draw the cloth or paper toward the grille,
incorrect rotation will blow the cloth or paper
away.
9. If the fan rotation is correct, leave the unit
turned on.
10. If the rotation is incorrect, the phase of the
power supply is wrong and must be corrected.
Turn Off the power to the cable and reverse
the position of any two power leads from the
power cable plug. Do not disturb the green
ground wire. (Refer this procedure to a
qualified electrical repairman).
Starting Zone 2 Evaporator
1. Start the condensing unit Zone 2 will
automatically be on.
2. Pressing the
O
N
key will turn off Zone 2
evaporator.
After Start Inspection
Compressor Oil:
The compressor oil level should
be visible in the sight glass.
Refrigerant:
Check the refrigerant charge, see
Refrigerant Charge in the Refrigeration
Maintenance chapter.
Thermostats:
Set each thermostat at, well above
or well below the compartment temperature.
Check to make sure that the mode of operation
changes with the change in setpoint.
Pre-Cooling:
With the thermostats set at the
required temperatures, allow the unit to run for
one-half to one hour (longer if possible) before
loading the truck. Pre-cooling will remove
residual body heat and moisture from the truck
interior and provide a good test of the
refrigeration system.
Defrost:
When the unit has finished pre-cooling
the truck interior (evaporator coil temperature
below 42 F [6 C]), initiate Defrost cycles with the
Manual Defrost keys. The Defrost cycles should
end automatically.
Loading Procedure
1. Make sure the unit is Off before opening the
doors to minimize frost accumulation on the
evaporator coil and heat gain in the truck.
(Unit may be running when loading the truck
from a warehouse with door seals.)
2. Spot check and record the load temperature
while loading. Especially note any
off-temperature product.
3. Load product so that there is adequate space
for air circulation completely around the load.
Do not block the evaporator inlet or outlet.
4. Products should be pre-cooled before loading.
Thermo King units are designed to maintain
loads at the temperature at which they were
loaded. Transport refrigeration units are not
designed to pull hot loads down to
temperature.
Post Load Procedure
1. Make sure all the doors are closed and locked.
2. Set the thermostats at the required temperature
setpoints.
3. Start the unit.
4. One-half hour after loading, Defrost each
evaporator by momentarily pressing the
Manual Defrost keys. If the evaporator coil
temperature has dropped below 42 F (6 C), the
unit will Defrost. The Defrost cycle should
stop automatically.