Thermo King 914 724, Manual

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Refrigeration Maintenance (Rev. 1/99)
48
NOTE: Service manifold hoses must have Schrader
valve (tire valve) depressors.
2. Set the thermostat well below the box temperature so
that the unit will be in cool.
3. Raise the discharge pressure of the compressor first by
blocking the condenser coil air flow.
NOTE: The discharge pressure should never be
allowed to exceed a pressure of 400 psi (2758 kPa) on
R-134a units, or 450 psi (3103 kPa) on R-404A units.
4. Failure of the high pressure cutout system to stop com-
pressor operation should be investigated first by check-
ing the control circuit operation and second by
replacing the HPCO.
SYSTEM CLEANUP
If the system ever becomes contaminated, cleanup the sys-
tem as follows:
1. Install a compressor on the system having a residual oil
supply and self-lubricating system such as a TK 214
model. Connect an oil separator on the discharge or
suction line to collect and drain out circulated oil.
NOTE: A suction line oil separator can be improvised
by installing a suction filter upside down in the suc-
tion line near the compressor. Cap off both access
ports, and use the lower one to drain off accumulated
oil.
2. Place a normal amount of oil in the cleanup compressor
before operating.
3. Charge with 6 to 7 lb (2.7 to 3.2 kg) of refrigerant.
4. Operate at low speed (600 to 800 rpm) for 2 hours, or
until the compressor oil level reaches a minimum
allowable level, whichever occurs first. Drain the col-
lected oil from the oil separator as it fills, taking care to
not allow any collected oil to recirculate.
5. Test the compressor oil with an acid test kit No.
203-346. Repeat Step 4 if the test shows acid in the
compressor oil.
6. Remove the cleanup compressor and suction filter.
Replace with a standard compressor, containing the
proper amount of oil.
7. Leak test, evacuate and charge the system.