4-16
©
2012 Mobile Climate Control
T-348 Rev. 07/2012
4.15.4 Compressor Oil Level
To check, and if required correct, the compressor oil
level do the following:
a. Operate the coach for at least one-half hour at fast
idle speed, with the temperature controls at the
coolest setting, and the compressor fully loaded. It
may be necessary to pre-heat the coach and/or op
erate the system in the reheat mode to keep the
compressor fully loaded throughout this proce
dure
b. Ensure the system is fully charged (refer to para
graph 4.8.1) and the compressor crankcase is
warm to the touch after fifteen minutes of opera
tion.
c. Shut off the system and immediately record the oil
level in the compressor sight glass. See
Figure 4-12. If the compressor is not level, an aver
age between the sight glass levels will have to be
made to determine level.
d. The correct oil level for this application should be
between the bottom and 1/2 of the oil level sight
glass. See Figure 4-12. If the oil level is correct, re
lease the coach into service. If the level is above the
1/2 sightglass maximum, proceed to step e. If the
level is below the 1/2 sightglass maximum proceed
to step f.
WARNING
Extreme care must be taken to ensure
that all the refrigerant has been removed
from the compressor crankcase or the re
sultant pressure will forcibly discharge
compressor oil.
e. To remove oil and bring the level to the 1/2 sight
glass maximum, do the following:
1. With the system off, connect a manifold gauge set
to the compressor suction and discharge service
valves. Front seat the service valves to isolate the
compressor from the system (See Figure 4-6) and
reclaim the refrigerant to below atmospheric
pressure. Shut off the reclaimer and verify the
pressure does not rise. If the pressure rises, con
tinue reclaiming until the pressure remains below
atmospheric.
2. Drain or pump out compressor oil until the level
is brought to the proper level.
3. Evacuate the compressor to 500 microns. Back
seat the compressor service valves and repeat the
oil level check procedure.
f. To add oil to the compressor, do the following:
1. With the system off, connect a manifold gauge set
to the compressor suction and discharge service
valves. Front seat both service valves to isolate the
compressor from the system (See Figure 4-6) and
reclaim the refrigerant to below atmospheric
pressure. Shut off the reclaimer and verify the
pressure does not rise. If the pressure rises, con
tinue reclaiming until the pressure remains below
atmospheric.
2. Add oil to compressor crankcase slowly, through
the oil fill plug opening (see Figure 4-12) to bring
level to mid range of allowed levels.
3. Evacuate compressor to 500 microns. Backseat
compressor suction and discharge valves, start
system and recheck oil level.
4. Remove manifold gauge set.
4.15.5 Checking Unloader Operation
To check unloader operation do the following:
a. Install a manifold gauge set as shown in Figure 4-6.
Ensure both manifold valves are frontseated and
center connection is tight on blank fitting.
b. Midseat compressor suction service valve.
c. Disconnect the suction pressure transducer
Figure 1-6. This will force the controller to ener
gize the unloader(s).
d. Start the bus and run in cooling, lower set point if
required to ensure system remains in full speed
cooling.
e. Locate the unloader connector at the compressor.
Observe manifold suction gauge while unplugging
the connector. Pressure should decrease 3 to 5 psi
(0.2 to 0.4 bar) when the unloader is unplugged
and increase the same amount as the plug is recon
nected. Repeat test for second unloader if fitted.
f. If pressures do not react as described, check un
loader coil or repair unloader mechanism as re
quired.
g. When testing is complete, reconnect transducer
and unloader connectors and remove manifold
gauge set.
h. Disconnection of the suction pressure transducer
will cause an “A15” alarm. Once the transducer is
reconnected, the alarm will go to inactive and can
then be cleared.
