Thermo King Super II SR+, Manual

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Refrigeration Maintenance (Rev 6/98)
76
High Pressure Cutout Manifold
1. Relief Valve (66-2202)
2. O-Ring (33-1015)
3. Adapter Tee Weather Head
(No. 552X3)
3. Raise the discharge pressure of the compressor first by
blocking the condenser coil air flow by covering the
condenser grille with a piece of cardboard. If this does
not raise the discharge pressure to the cutout level of
the HPCO, increase the engine speed by overriding the
throttle solenoid. This should increase the discharge
pressure enough to cause the HPCO to cut out.
NOTE: The discharge pressure should never be
allowed to exceed a pressure of 3103 kPa (450 psi).
4. Failure of the HPCO system to stop unit operation
should be investigated first by checking the control cir-
cuit operation and secondly by HPCO switch replace-
ment.
THREE-WAY VALVE CONDENSER
PRESSURE BYPASS CHECK VALVE
A three-way valve condenser pressure bypass check valve is
used in this unit. This check valve controls the bypass flow
of refrigerant gas between the condenser inlet line and the
compressor discharge line.
The check valve is closed when the unit is running on cool,
or whenever the discharge pressure is higher than the con-
denser pressure.
When the unit is running on defrost or heat, if the condenser
pressure is higher than the discharge pressure, the check
valve opens and the condenser pressure is bled off until it
drops to the level of the discharge pressure. The purpose of
Three-way Valve Condenser Pressure Bypass Check Valve
1. Cooling Position
2. Check Valve
3. Heating/Defrost Position
1 2 3 2
AEA671