Checking Compressor Oil Level - Carrier DM-4 Power Pack Operation And Service Manual

15. Install compressor in unit by reversing steps 1
through 14. It is recommended using new locknuts when
replacing compressor. Torque bolts to a value of 46 ft/lb
(6.4 mkg). Install new gaskets on service valves and tighten
bolts uniformly.
16. Attach service gauge manifold lines to the suction
and discharge service valves. Connect manifold to vacuum
pump. Evacuate compressor to 500 microns (29.90" Hg
vacuum 75.9 cm Hg vacuum) . When completed, close
gauge valves and disconnect vacuum pump.
17. Fully open (backseat) both suction and discharge
service valves and partially open to activate gauges.
18. Start unit and check refrigerant level. Also check
for noncondensibles.
19. Check compressor oil level. Add oil as necessary.
20. Check compressor unloader operation and check
refrigerant cycle.

4.6 CHECKING COMPRESSOR OIL LEVEL

a. To Check the Oil Level in the Compressor
1. Operate the unit in fully loaded high speed cool for
at least 20 minutes.
2. Check the oil sight glass on the compressor to ensure
that no foaming of the oil is present after 20 minutes of op-
eration. If the oil is foaming excessively after 20 minutes of
operation, check the refrigerant system for flood-back of
liquid refrigerant. Correct this situation before proceed-
ing.
3. Check the level of oil in the sight glass with the com-
pressor operating. The correct level should be 1/2 of the
sight glass. If the level is above 1/2, oil must be removed
from the compressor. To remove oil from the compressor,
follow step d. If the level is below the sight glass, add oil to
the compressor following step b.
b. Adding Oil with Compressor in System
1. Oil Pump Method
One compressor oil pump that may be purchased is a
Robinair, part no. 14388. This oil pump adapts to a one
U.S. gallon (3.785 liters) metal refrigeration oil container
and pumps 2-1/2 ounces (0.0725 liters) per stroke when
connected to the oil fill (item 4, Figure 4-5). Also there is
no need to remove pump from can after each use.
When the compressor is in operation, the pump check
valve prevents the loss of refrigerant, while allowing ser-
vicemen to develop sufficient pressure to overcome the
operating suction pressure to add oil as necessary.
2. Closed system method
In an emergency where an oil pump is not available, oil
may be drawn into the compressor through the suction ser-
vice valve.
CAUTION
Extreme care must be taken to ensure the
manifold common
immersed in oil at all times. Otherwise air and
moisture will be drawn into the compressor.
connection remains
Connect the suction connection of the gauge manifold
to the compressor suction service valve port, and immerse
the common connection of the gauge manifold in an open
container of refrigerant oil. Crack the suction service valve
and gauge valve to vent a small amount of refrigerant
through the common connection and the oil to purge the
lines of air. Close the gauge manifold valve.
With the unit running, frontseat the suction service
and pull a partial vacuum in the compressor crankcase.
SLOWLY crack the suction gauge manifold valve and oil
will flow into the compressor. Add oil as necessary.
6
1
3
1. Suction Service Valve
2. Oil Fill Plug
3. Oil Drain Plug
4. Oil Level Sight Glass
5. Unloader Solenoid
6. Discharge Service Valve
Figure 4-7. Compressor
c. Adding Oil to Service Replacement Compressor
Service replacement compressors may or may not be
shipped with oil.
If compressor is without oil
Add correct oil charge (refer to section 1.3) through
the suction service valve flange cavity or by removing the
oil fill plug. (See Figure 4-7)
d. To Remove Oil from the Compressor
1. Close suction service valve (frontseat) and pump
unit down to 2 to 4 psig (0.1 to 0.3 kg/cm
frontseat discharge service valve and slowly reclaim re-
maining refrigerant.
2. Remove oil drain plug from the compressor and
drain the proper amount of oil. Replace the plug securely
in the compressor.
3. Open service valves and run unit to check oil level,
repeat as required to ensure proper oil level.
4-6
5
2
4
05K
2)
. STOP unit