Automotive Air Conditioning Information Forum (Archives)

pgtr on Sun May 01, 2011 10:45 PM

Year: 1996
Make: Chevrolet
Model: Corvette
Engine Size: 350
Refrigerant Type: R134a
Country of Origin: United States

1996 GM A/C High Pressure Service Port/Valve - How to Service?

I have a 1996 Corvette (P-Code LT1) with the original R134a system. A/C recently stopped working due to low refrigerant pressure. I've since traced the leak to the high side service port where there was a lot of oil residue.

Inside the port all I see is an odd black rubber ball. The ball can be depressed to open the line and appears to work fine w/ service hose connected. However I do NOT see a removable shrader valve down there. The port assembly is apparently soldered to an aluminum line. (There is a traditional shrader valve on the low side port, too deeply depressed for my old shrader tool to reach.)

Question: How do I service this leaking valve? Is there a regular shrader valve threaded in below this rubber 'doohicky'? Or do I have to solder a replacement high side port to the line? Manual says it can be removed w/ special tool J-39037 which appears to be nothing more than a socket...? And again I've looked carefully at it and it appears soldered on.

Thanks!


PS: Since I'll likely be cracking open the A/C system I might also replace the OE accumulator. Is there anything else I should take care of while I have the system open?

Dougflas on Mon May 02, 2011 12:02 AM

Why not put a cap on the port? The cap is the main protection against loss of refrigerant.

GM Tech on Mon May 02, 2011 3:48 AM

If you have oil residue about port, then yes, you have lost some refrigerant there...but as mentioned, the cap is the primary seal, make sure your rubber element (disc) is inside the cap, and the cap does not have a hole in it- otherwise replace the cap.

And yes the high side port is serviceable, exactly as you describe- it screws out of the welded base, but system must be discharged in order to replace it. It is available by our site sponsor..

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......