A/C Woes
Thread Starter
Joined: Jun 2014
Posts: 1,242
Likes: 47
From: Noblesville, IN
A/C Woes So last year I pulled a vacuum on the A/C on my C5 with the intention of finding a leak. To my surprise, the system held almost perfect vacuum (and I let it sit for a week just to be sure). Charged the system and for the month or so I got to drive it before the weather went nasty, I had ice cold A/C.
Start driving it this summer, and boom nothing. The compressor is turning on and staying on, and the fans are kicking on as well. Hooked my gauges up to it and on an 80 degree day with 70% humidity, the low side is sitting at right around 30psi, and the high side is at 95 at 2k rpm.
Any ideas? I thought I might have a leak that only presents itself under pressure vs. vacuum, but I'd also injected some dye into the system when I charged it last year, and I can't see anything anywhere that indicates a leak.
Start driving it this summer, and boom nothing. The compressor is turning on and staying on, and the fans are kicking on as well. Hooked my gauges up to it and on an 80 degree day with 70% humidity, the low side is sitting at right around 30psi, and the high side is at 95 at 2k rpm.
Any ideas? I thought I might have a leak that only presents itself under pressure vs. vacuum, but I'd also injected some dye into the system when I charged it last year, and I can't see anything anywhere that indicates a leak.
Joined: Nov 2001
Posts: 34,661
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From: Schiller Park, ILL Member: #317
I had something similar happen with my daily driver (GM R134a car, but not an F/Y-body) over this last winter. Last summer the low side line had sprung a leak and the compressor was weeping oil, so I had both replaced (with new GM compressor) and the system was charged. Everything was fine for the remainder of that season. But then this spring, it wasn't getting as cold as it should. Hooked it up to an A/C machine and it was 50% low. Vacuumed it and refilled, and so far it's been fine this summer, but I expect it to leak out over the next winter again as we never found the leak (in spite of there still being dye in the system from last year's diagnostics). No idea how it could lose than much freon in ~6 months without an obvious leak (dye) and without any loss during the warmer months.
TECH Fanatic
Joined: Dec 2017
Posts: 1,476
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From: Bossier City, Louisiana
Testing for leaks under a vacuum are not always going to catch a leak that only occurs under pressure. Get the halogen leak detector from Harbor Freight. You will find the leak.
Rick
Rick
Joined: Nov 2001
Posts: 34,661
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From: Schiller Park, ILL Member: #317
Should be, but my last remaining leak is apparently so small that it's not so easy - even with dye. So one of two things is likely happening I guess:
1) Evap core is leaking, thus not visible without disassembly.
2) Leak is so minor that it only occurs in the cold months when things shrink/contract, so I'll have to wait until next year to find the leak.
Will dye remain viable for ~12 months in the system? Or does it ever lose it's visual properties?
Thread Starter
Joined: Jun 2014
Posts: 1,242
Likes: 47
From: Noblesville, IN
You hit the nail on the head! Just checked the hi side valve and sure enough theres a bunch of dye around the valve (and i can see it bubbljng as well)
Im thankful it's an easy fix!
Dye i believe remains viable until you wipe it off. Mine still glows around the lo side port where i injected the dye (over a year later) as well as where the active leak around the hi side valve is.
Also, if you suspect your evaporator is leaking, check the condensate drain. If there's a leak you should be able to see some UV residue on the drain hose.
Im thankful it's an easy fix!
Also, if you suspect your evaporator is leaking, check the condensate drain. If there's a leak you should be able to see some UV residue on the drain hose.
