Trane Thermo King V-520 RT SPECTRUM 50 Installation Manual page 64

SPR and CPR Adjustment Procedures (continued)
Suction Bypass CPR Valve
(SPECTRUM Units Only)
The suction bypass CPR valve is located in the advanced control system
module, which is mounted on the back of the evaporator. The advanced
control system balances the suction pressure between the fresh and frozen
evaporators to allow both evaporators to have equal capacity to control the
two zones. This system gives priority to the frozen section. It also keeps
refrigerant from migrating into the frozen evaporator when it is not
running.
1. Install a gauge manifold set on the engine driven compressor.
2. Shut off the fresh compartment by raising its setpoint to the highest
setting.
3. Start the unit on the engine driven compressor at 1800 to 2000 RPM.
4. Bring the frozen compartment to 5 to 7 F (3 to 4 C) above desired
setpoint. Record the suction pressure and then shut the unit off.
5. Remove the suction bypass solenoid coil and install a magnet (P/N
204-1074) to close valve.
6. Raise the frozen compartment setpoint to the highest level on the HMI
and lower the fresh compartment setpoint to 35 F (2 C) and start the
unit.
7. With the unit running, set the suction pressure to the recorded value
from step 4 by adjusting the suction bypass CPR valve. Once the
suction pressure has been set, turn the unit off.
8. Remove magnet and reinstall the coil on the suction bypass solenoid.
9. Remove the gauge manifold set.
10. Start the unit with both compartments set to desired setpoints and let
the unit pull down.
11. It is normal for the frozen compartment to pull down faster than the
fresh compartment on first start up.
Typical V-520 RT SPECTRUM Advanced Control System Module Components
Suction Bypass CPR
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