REPLACING AC COMPRESSOR?

2003 HUMMER H2
170,000 MILES • 4WD • AUTOMATIC
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BHAMDOC1
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WOULD YOU INSTALL ORIFIC TUBE AND DRYER FORST THEN VACUUM OR VACUUM OLD SYSTEM FIRST?
CAN THE ORFIC TUBE BE REMOVED WITHOUT ANY SPECIAL TOOLS? HOW MUCH OIL DO I NEED TO ADD INTO THE NEW COMPRESSOR?
Aug 23, 2026 at 8:40 AM

What to check next

Diagnostic guidance. Suggested checks and possible repairs are separate from the owner's reported results.

The reported return of cold air is encouraging. Before treating the job as complete, have the installed compressor instructions and service record checked for the correct oil type, total oil balance and refrigerant charge. A fixed generic oil quantity or dividing oil equally between parts is not a universal procedure. Ask whether the original compressor failure required inspecting or replacing the metering device and addressing contamination. If the circuit needs reopening, have refrigerant recovered first, then complete the specified repair, evacuation and charging sequence. Do not open a charged system to inspect the tube. Verifying those details now can help protect the new compressor and preserve the improvement already reported.

Guidance references and applicability

DENSO: A/C compressor installation guide https://assets.denso-am.eu/production/attachments/AC-Compressor-Installation-Manual-multilingual.pdf Supports application-specific oil accounting, contamination assessment and proper refrigerant recovery. Follow the installed compressor manufacturer's instructions; no universal oil quantity is prescribed here.

Read the replies · Discussion summary and reported outcome

AI-ASSISTED GUIDANCE · REVIEWED BY 2CARPROS
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STEVE W.
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I'll pull a vacuum just to see if it holds as a quick leak check. Then I'll pull it apart, flush the system out and replace the drier, tube and the EVAP core (if the compressor came apart) then swap the compressor. Then pull a vacuum and see if it holds. That lets me check for leaks and pulls any moisture out that got in while it was apart. For oil, the new compressor should come with oil, generally you drain the oil from the old one, measure it and add the same amount to the replacement. If however you had to flush the system I measure the compressor and then look at the total oil charge and what you drained out. Add the same amount you drained back into the compressor and the rest gets put into the rest of the system. GM went to a premeasured 8 ox cartridge on those vehicles, so say you drained 4 oz from the compressor, you would add 4 into it, then 2 into the EVAP core and 2 into the condenser core.
Aug 23, 2026 at 9:45 AM
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BHAMDOC1
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I started with a vacuum and after 30 minutes it was at -29. Left it fir 30 and still there
Aug 27, 2026 at 12:58 PM
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STEVE W.
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Should be OK to proceed then. Although this is a Hummer, it's actually a Tahoe 6.0 engine and 4L65E transmission. Simple replacement, pull any 134A charge out. Remove the AC belt and unplug the connector, remove the lines from the unit then the bolts that hold the compressor to the mount. With those out remove the compressor. Now dump out the oil, what you are looking for is debris or blackened oil, both mean the system needs a full flush and then the drier, o-tube and the EVAP core should all be replaced to keep any blockage from happening. Then you put it back together, adding oil to the compressor and other components, pull it down, check it, if it's good, charge it up and test it.
Aug 27, 2026 at 11:03 PM
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BHAMDOC1
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Replaced all including all o-rings, dryer. Clean oil came out of the dryer and compressor. Removed oil from compressor and added fresh oil half to dryer half to compressor, installed and it's cold, hopefully it holds and no leaks. Guess what, forgot to replace the orifice tube ugh
Aug 28, 2026 at 2:54 PM
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STEVE W.
  • ✓Experienced Mechanic
  • 15,370 POSTS
Good to hear. Clean oil is always a plus. OOPs... lol.
Aug 28, 2026 at 6:02 PM
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Discussion summary

REPLACING AC COMPRESSOR?

The owner asked about compressor replacement, evacuation, oil quantity and the orifice tube. The owner later reported replacing the compressor, dryer and seals and obtaining cold air, but had not replaced the orifice tube. Exact charge and oil accounting were not documented.

Reported outcome: The owner reported cold air after the repair. Long-term performance was not reported.

Correct oil quantity, refrigerant charge and contamination assessment were not verified. Holding vacuum and producing cold air do not independently validate every installation detail.

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AI-ASSISTED SUMMARY · REVIEWED BY 2CARPROS
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