Unit Description
29
High Pressure Cutout Switch:
The high pressure cutout
switch (HPCO) is located on the compressor discharge
manifold. If the compressor discharge pressure becomes
excessive, the switch opens the circuit to the run relay to stop
the unit. The microprocessor will record Alarm Code 10.
High Pressure Relief Valve:
This valve is designed to
relieve excessive pressure in the refrigeration system. It is
located on the receiver tank. If the high pressure relief valve
opens, much of the refrigerant will be lost. Take the unit to a
Thermo King dealer if this occurs.
Low Oil Level Switch:
The low oil level switch closes if the
oil drops below an acceptable level. If it stays closed for a
specified time, the microprocessor shuts the unit down and
records Alarm Code 66.
Low Oil Pressure Switch:
The low oil pressure switch
closes if the oil pressure drops below an acceptable level. If it
stays closed for a specified time, the microprocessor shuts the
unit down and records alarm code 19.
Preheat Buzzer:
The preheat buzzer sounds when the base
controller energizes the preheat relay. This warns anyone near
the unit that the controller is about to start the engine.
Overload Relay—Automatic Reset (SmartPower):
An
overload relay protects the standby electric motor. The
overload relay opens the circuit to the electric motor if the
motor overloads for any reason (e.g., low line voltage or
improper power supply) while the unit is on electric standby
operation. The microprocessor will record Alarm Code 90.
Smart FETs:
Smart FETs in the microprocessor protect some
circuits and components from an overcurrent condition.
Fuses:
A number of fuses, located on the microprocessor,
protect various circuits and components. The microprocessor is
located inside the control box. Refer to the appropriate
Microprocessor Controller Diagnostic Manual for more
information about the fuses.