Zanotti DBO Serie Mode D'emploi page 33

4. Unsatisfactory efficiency of the unit
If the unit does not perform adequately and no defects can be identified, check that: cold room doors are
perfectly tight; no cold dispersion is available; the cold room is used wisely; no unfrozen liquids or foodstuffs
are placed in the low temperature room; the evaporator is ice-free.
We advise to install the units far from the doors, especially when the cold room is expected to be opened
many times a day.
WARNING:
Removal of protections during machine operation is absolutely forbidden. They have been
developed to safeguard the operator's safety.
5. Other troubles may be due to the triggering of the following electrical safety devices:
a) Fan thermal protection (incorporated in the motor) - automatic reset
It protects electric fans against high power absorption due to:
- overheating
- lack of a phase (only for three-phase models)
- dirty condenser
- ice in the evaporator
b) Oil pressure switch - manual reset (only for compressors equipped with oil pump). It protects mechanical
parts of compressor in case of lack of lubrication due to:
- clogged oil filter
- excessive sediment level in oil
- cold oil mixed with refrigerant
To reset the device, press the button on the pressure switch after at least 10 minutes from activation. In
the meantime, keep sump heater on.
c) High pressure switch - manual reset
It protects the compressor from excessive pressures (which cause the pressure switch to be triggered very
often) due to:
- dirty condenser
- non-operating condenser fans
- excessive temperature in the room where the unit is installed
- unit used in unsuitable conditions or with inappropriate products.
To reset the device, press the button on the pressure switch
d) Low pressure switch - automatic reset
This device is activated every time the unit stops when reaching the right temperature. Sometimes it can be
activated because of:
- lack of gas due to tube breakage or loosened unions
- clogged filters
- broken solenoid valve
- ice in the evaporator
WARNING
Min. and max. pressure switches are placed in motor room. Before resetting, disconnect
mains switch.
e) Thermistors - automatic reset (only for semi-hermetic compressors)
Placed in compressor winding, they protect the motor from overheating (see wiring diagram).
f) Electronic min/max voltage relay (Monitor) - automatic reset (where available). It protects the unit from
irregular supply voltage (about 12% of rated value).
WARNING:
Removal of protections during machine operation is absolutely forbidden. They have been
developed to safeguard the operator's safety.
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