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 TM 55-1905-219-14-8
4-5. GENERAL (Continued).
Table 4-8. Air Conditioner Lubrication Troubles
Troubleshooting.
NOTE
Refer to paragraphs 4-28 and 4-29 for air conditioning and compressor
maintenance instructions.
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
1.
Oil leaves compressor crankcase.
Step 1.
Too much refrigerant flooding back to compressor.
Adjust thermal expansion valve(s) to 8-10F superheat to avoid flooding.
Step 2.
Leaking piston rings or worn cylinder sleeve.
Replace worn rings or cylinder sleeve.
2.
Oil does not retrun to crankcase.
Step 1.
Thermal expansion valve not flooding coil. Oil trapped in coils.
Adjust to flood coil. Refrigerant liquid should extend to midpoint of last coil bank of
circuit.
Step 2.
Oil return check valve in compressor stuck closed.
Pump down, and remove check valve. Clean, repair, or replace.
3.
Low oil pressure, or no oil pressure.
Step 1.
Insufficient oil pressure.
Oil level should be half-way up on the bull's-eye sightglass. Minimum level is one-
quarter up on glass. Add Carrier No. PP36-1 oil as required.
Step 2.
Faulty oil gage.
Check and replace gage if faulty.
Step 3.
Oil filter screen in bottom of crankcase clogged with dirt.
Pump down, remove screen, clean and reinstall.
4-38
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