Flushing A/C System

1985 Buick Century V6-231 3.8LSECTION Flushing A/C System

1. Discharge refrigerant as outlined.
2. Disconnect all A/C refrigerant line fittings and discard O-rings.
3. Remove orifice tube, if equipped, and discard if contaminated.
4. Ensure all valves on manifold gauge set are closed, and connect gauge set to canister of R-11 refrigerant. R-11 is the only approved solvent for flushing A/C system. Use caution and observe all previously mentioned precautions when flushing system.
5. Use flushing tool J-33833 or equivalent and, starting with evaporator core, force liquid R-11 in from bottom of core until it flows out top.
6. When liquid runs from top of core, shut "OFF" flow of refrigerant, wait 5 minutes, then drain core.
7. Repeat steps 5 and 6 with condenser core. Wait 5 minutes before draining refrigerant from core.
8. If compressor must be flushed, proceed as follows:
a. Drain compressor through suction and discharge ports, and if applicable, through crankcase fitting.
b. Fill compressor with R-11 through suction port until refrigerant runs out discharge port. On V-5 compressor, it is necessary to remove crankcase plug and fill crankcase with refrigerant through plug opening.
c. Rotate compressor 1-2 turns with clutch drive plate, if possible. Do not force compressor shaft to turn.
d. Wait 5 minutes, then drain refrigerant from compressor.
9. Cap refrigerant lines and fill lines with R-11 opening valve on R-11 canister and low side service valve on manifold to allow refrigerant to flow through lines.
10. Allow sufficient refrigerant to flow through lines to remove contaminants, then close off valves. Wait 5 minutes, then drain refrigerant lines.
11. Flush R-11 from system components using R-12 refrigerant.


RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.