Zanotti Zer0 120, Руководство по ремонту

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SECTION 5 - Diagnosis
Beware of unannounced starting of the unit. The unit
may cycle the fans and operating compressor
unexpectedly as control requirements dictate. Press
OFF key on the cab command and turn vehicle engine
off.
5.1 TROUBLESHOOTING TOPICS
If desired box temperature cannot be obtained during
operation, any of the following may be indicated:
EXCESSIVE HEAT LOAD:
An excessive heat load on the system will be caused by
too many, or excessively long, stops with the doors
open. Excessive heat loads will also be caused by
loose doors, loose body panels, warm loads and poor
insulation.
A solution to this can be door curtains used easy
access barrier when unloading the vehicle. Another
solution if applicable can be a bulkhead to decrease
the area of the box as the load gets smaller. To
increase efficiency of the unit.
DIRT & DEBREES ON COILS:
Dirt on the condenser or evaporator coil acts as an
insulator reducing the capacity of the unit. Clean the
coils regularly or during maintenance
INCORRECT BELT TENSION:
If the drive belt is not correctly tensioned, the
compressor will not be driven at proper speed, and
unit efficiency will be reduced. By contrast, too much
tension will place an additional load on the bearings
causing rapid wear.
SHORTAGE OF REFRIGERANT:
Shortage of refrigerant reduces capacity of the unit.
Find and remedy the cause of the shortage and
recharge
the system. DO NOT operate the unit if there is an
indication of low charge.
FAULTY EXPANSION VALVE ADJUSTMENT:
High superheat settings will starve the evaporator causing
low suction pressure. Low superheat settings will flood the
coil causing high suction pressure. The superheat setting
should be adjusted ONLY by a trained refrigeration service
technician.
EXCESSIVE OIL:
Too much compressor oil in the system may result in lower
than normal suction pressure as well as lowered capacity.
MOISTURE IN THE SYSTEM:
Expansion valve freeze-up will not refrigerate. Usually this
can be checked by warming the expansion valve with
either the hand or hot towels to see if the valve opens.
Evacuate the system in the same manner used during
installation. Install a new drier.
EXPANSION VALVE BULB LOSES ITS CHARGE:
If the expansion valve loses its charge, the valve will close
causing the system to go into vacuum. Replace the valve.
AIR IN SYSTEM:
Air is not condensable. Its presence in the system increases
head pressure. When the compressor is stopped, air will
gather at the high point of the high side. Reclaim the
refrigerant, evacuate the system to 500 microns and
recharge with the proper amount of refrigerant.
TEMPERATURE OF THE LIQUID LINE:
During normal operation, the liquid line will be slightly
warmer than surrounding air. An extremely hot line
indicates either shortage of refrigerant or lack of a liquid
seal at the receiver outlet. A cold line indicates a
restriction, and some flashing takes place in the liquid line
sight glass.
DIRTY OR WET FILTER DRIER:
If the outlet line of the filter drier is colder than the inlet
line, the filter is either saturated with moisture or is dirty
and must be replaced.