Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 764 (HEATING, VENTILATION AND AIR CONDITIONING)REPAIR INSTRUCTIONSCOMPRESSOR LEAK TESTING (V7 - DIRECT MOUNT)
1999 GMC Forward Control 5.7 R, Automatic
Compressor Leak Testing (V7 - Direct Mount)
1999 GMC Forward Control 5.7 R, AutomaticSECTION Compressor Leak Testing (V7 - Direct Mount)
WARNING: This page is about a different car, the 2004 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.
Tools Required
- J 39400-A Halogen Leak Detector. See Special Tools and Equipment .
- J 43600 ACR 2000 Air Conditioning Service Center. See Special Tools and Equipment .
- J 39893 Pressure Testing Connector
- With the sealing washers in place, install the J 39893 on the rear head of the A/C compressor.
- Connect the gage charging lines and the J 43600 . See Special Tools and Equipment .
- Pressurize the suction and the high-side of the A/C compressor with R-134a refrigerant.
- With the A/C compressor in a horizontal position, rotate by hand the A/C compressor shaft in the operating direction.
- Rotate the shaft several times.
- Using the
J 39400
, check for leaks at the following locations:
- Pressure relief valve
- Rear head switch
- Front head seal
- Rear head seal
- Through bolt head gaskets
- A/C compressor shaft seal
- Perform the measures necessary to correct any external leaks found.
- Recheck for leaks following any repair.
- Recover the refrigerant.
- Disconnect the hoses from the J 39893 .
- Remove the J 39893 .
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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.