Refrigeration Maintenance
133
Checking Compressor Oil
The compressor oil should be checked when there
is evidence of oil loss (oil leaks) or when
components in the refrigeration system have been
removed for service or replacement. The oil level
in the compressor oil sight glass should be 1/4 to
3/4 full.
To check compressor oil level with an ambient air
temperature above 50 F (10 C):
Install a gauge manifold.
Operate the unit with all zones on high speed cool
with a 10 psig (69 kPa) minimum suction pressure
and 185 psig (1275 kPa) minimum discharge
pressure for 15 minutes or more.
After the unit has maintained the above conditions
for 15 minutes, observe the oil level. The oil
should be 1/4 to 3/4 up in the sight glass.
To check compressor oil level with an ambient air
temperature below 50 F (10 C):
Run the unit through a complete Defrost cycle.
After completing the Defrost cycle, run the unit
with all zones on Cool for ten minutes. Observe
the oil level. The oil should be 1/4 to 3/4 up in the
sight glass.
If the an evaporator temperature is above 32 F
(0 C), it will be necessary to force defrost. To
force defrost, use the Service Test Mode.
If the box is empty, you can run the unit on the
Heat cycle instead of the Defrost cycle.
NOTE: Use refrigeration compressor oil ONLY.
R-404A systems use a special Ester oil (see Tool
Catalog). Required for Scroll compressors.
Oil can be added to the compressor through the
Schrader valve on the throttling valve (see Figure
162 on page 138) while the unit is running. Take
precautions to prevent contaminants from entering
the system while adding oil. Also see “Scroll
Compressor Oil Change” on page 141.
High Pressure Cutout Switch
(HPCO)
The high pressure cutout switch is located on the
discharge line. If the discharge pressure rises
above 470 psig (3241 kPa), the switch opens the
8H circuit to stop the unit. To test the switch,
rework a gauge manifold per illustration.
1. Connect the gauge manifold to the discharge
service port with a heavy duty, black jacketed
thick wall #HCA 144 hose with a 900 psig
(6204 kPa) working pressure rating.
1. Compressor Oil Sight Glass Location
Figure 159: Scroll Compressor
CAUTION: Oil is under pressure. See
instructions for adding oil.
1
AGA658
1. Relief Valve
2. O-ring
3. Adapter Tee Weather Head
Figure 160: High Pressure Cutout Manifold
To Next Page
Loading...
Need help?
General
