Automotive Air Conditioning Information Forum

Amen.

This is a 7-year-old thread.

Tbird, thanks for the donation.

Adding the correct refrigerant for a pressure test won't harm the desiccant; Nitrogen does work, too. If you must open the system for a repair, cap the drier.

Issue:
System will not hold vacuum, post-replacement. System equalizes from vacuum in just 30mins, which suggests (to me) a rather large opening... somewhere.

I realize that negative pressure indicates an opening in a system, while positive pressure reveals it. I lack the equipment to put the ...

Cusser wrote: Thu May 08, 2025 6:13 am

GMBDguy wrote: Mon May 05, 2025 9:30 pm Should I just always replace the schrader valves on older systems while empty? Seems like its cheap insurance.

I would. Even though the cap is the "real" seal.

Well, I doubt the cap w/o a valve core would hold up well.

You will need to post some initial pressure readings. Few things could cause this to happen.

The system needs to be completely clean of debris. I would not trust a FS reman.

Refrigerant-134a
All Models .................... 0.68 kg (1.5 lb)

Important: Refer to the emissions certification label (Saturn Power Module) for proper amount of R-134a charge.

Polyalkaline Glycol (PAG ...

They only made two sizes of high-side ports on older GM vehicles, 3/8" or 7/16".

Does the pressure change when you give the vehicle increased RPM? Gauges should be closed when checking.