ZR-1 Net Registry Forums - View Single Post - Troubleshooting AC leak before charging with R134a

1991 Corvette ZR-1 · 04-21-2022

I have recently done an overhaul of items in the AC system and I am running into a leak when vacuum testing the system. So for the things I have done:

Rebuilt the compressor
New Condenser
New Accumulator/Dryer
New compressor hoses
New orifice tube
New pressure switches
All new o rings coated with Nylog Blue sealant

The compressor was filled with a little over four ounces of oil containing UV dye. The rest of the UV dye oil was put into the accumulator. Strangely, I pulled vacuum on the system for over an hour and 20 minutes and it maintained -30 in Hg on the low side and high side. It was not until I did a subsequent test due to paranoia that I can no longer duplicate the required hour of vacuum being maintained. The high side appears to hold vacuum while the low side is losing half of the vacuum in about 40 minutes in the attached picture. I have double checked the fittings to make sure they are not leaking but part of me thinks that is the case.

What all is isolated to the high side? What is considered low side focused parts? Part of me wants to charge the system and look for the potential leak with a UV light after a few drives. BUT the idea of a slow leak of R134a refrigerant in the garage does not sit well with me either.

Wanted to make sure I tried everything before giving in and having a shop leak troubleshoot. I would not think a leak decides not to leak one test then decides to the second time I test.

04-21-2022	#1
1991 Corvette ZR-1 Join Date: Sep 2018 Location: Florida Posts: 306	Troubleshooting AC leak before charging with R134a I have recently done an overhaul of items in the AC system and I am running into a leak when vacuum testing the system. So for the things I have done: Rebuilt the compressor New Condenser New Accumulator/Dryer New compressor hoses New orifice tube New pressure switches All new o rings coated with Nylog Blue sealant The compressor was filled with a little over four ounces of oil containing UV dye. The rest of the UV dye oil was put into the accumulator. Strangely, I pulled vacuum on the system for over an hour and 20 minutes and it maintained -30 in Hg on the low side and high side. It was not until I did a subsequent test due to paranoia that I can no longer duplicate the required hour of vacuum being maintained. The high side appears to hold vacuum while the low side is losing half of the vacuum in about 40 minutes in the attached picture. I have double checked the fittings to make sure they are not leaking but part of me thinks that is the case. What all is isolated to the high side? What is considered low side focused parts? Part of me wants to charge the system and look for the potential leak with a UV light after a few drives. BUT the idea of a slow leak of R134a refrigerant in the garage does not sit well with me either. Wanted to make sure I tried everything before giving in and having a shop leak troubleshoot. I would not think a leak decides not to leak one test then decides to the second time I test. Last edited by 1991 Corvette ZR-1; 02-23-2024 at 10:33 PM.