PREVOST X3-45 2016, Руководство по обслуживанию

Страница: 420 / 459

Section 22: HEATING AND AIR CONDITIONING
PA1593
22
FIGURE 25: COMPRESSOR ALIGNMENT
22040
7.1.7 Compressor Maintenance
For the maintenance of the A/C compressor,
see the
Carrier Compressor “WORKSHOP
MANUAL for MODEL 05G TWIN PORT
COMPRESSOR” included at the end of this
section.
MAINTENANCE
Check compressor oil level and add if
necessary, every 6,250 miles (10 000 km) or
twice a year, whichever comes first.
CAUTION
Use only Castrol SW 68 (POE) oils with
refrigerant 134a.
7.1.8 Troubleshooting Guide
A preliminary check may be made by simply
feeling the cylinder heads with the unit in
operation at ambient temperatures of 35
o
F (2
o
C)
and over. The cylinder heads are internally
divided into suction and discharge valves. The
lower half of the cylinder head is the suction
side, and it should be relatively cool to the touch,
as opposed to the hot upper discharge side. If a
valve plate or head gasket is blown, or a
compressor unloader is stuck open, partially
compressed refrigerant vapor will be circulated
between the suction and discharge sides of the
head. The affected cylinder head will then have
a relatively even temperature across its surface
and be neither as hot as the normal discharge
temperature nor as cool as the normal suction
temperature.
Blown Head Gaskets
Symptom:
* Loss of unit capacity at low temperature.
* Even cylinder head temperature.
Cause:
* Improperly torqued cylinder head bolts.
* Improperly positioned gasket at assembly.
* Warped cylinder head.
* Severe liquid refrigerant floodback.
Blown Valve Plate Gaskets
Symptom:
* Loss of unit capacity at medium and low
temperatures.
* Very hot cylinder head surface.
* Higher than normal suction pressure.
Cause:
* Improperly torqued cylinder head bolts.
* Severe liquid refrigerant floodback.
* Oil slugging caused by an overcharge of oil
or flood starts.
* Discharge valves not seated properly (liquid
drainback during shutdown).
Broken Suction Valves
Symptom:
* Loss of unit capacity at all temperatures.
* Compressor unable to pull extremely low
vacuum with suction service valve
frontseated.
Cause:
*
Repeated liquid refrigerant floodback.
*
Flooded starts.
* Overcharge of oil.
* Discharge valves not seated properly (liquid
drainback during shutdown).