Automotive Air Conditioning Information Forum (Archives)

paulo57509 on Sun July 24, 2011 5:37 PM

Year: 1992
Make: Chevrolet
Model: Lumina Euro
Engine Size: 3.1L
Refrigerant Type: R134a
Ambient Temp: 87F
Pressure Low: ~35
Pressure High: ~200
Country of Origin: United States

My 134a conversion went well with the exception of a slow leak that surfaced after three weeks of buttoning up the system. I used an SPX/Robinair Electronic Leak Detector and traced the leak to the evaporator side of the accumulator. When I removed the accumulator, I found found the leaking side had a funky kind of o-ring on the fitting. It's the deformed o-ring on the right in the photo below.



The o-ring feels more like a hard plastic ring rather than a "rubber" ring like the o-ring shown on the left. I don't recall noticing this difference in o-ring material when I re-assembled the system

After replacing the o-rings and accumulator, I partially charged the system and sniffed around with leak detector again. I still detected a leak at that location. After some trial and error, I stared to detect leaks at every threaded connection in the system if I left the detector probe in position after 30 seconds or so. This was the first time that I had used Nylog in the threaded fitting and o-rings.

I held the opened container of Nylog under the sniffer and it set off the detector. Is there an issue with electronic leak detection when using Nylog?

The system is working properly again. Hopefully, the leaks detected after assembly are false.

300SD on Sun July 24, 2011 7:10 PM

That is interesting! I'm about to get into sealing up o rings and such and have never don it.

300SD on Sun July 24, 2011 7:10 PM

That is interesting! I'm about to get into sealing up o rings and such and have never done it.

Edited: Sun July 24, 2011 at 7:31 PM by 300SD

TRB on Sun July 24, 2011 7:36 PM

We never got a false positive do to Nylog. As much as this stuff has been used over the years. Seems pretty odd to now all off the sudden it shows up on a leak detector. If I remember I check a new bottle at the office next week.

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Dougflas on Sun July 24, 2011 8:52 PM

Do your fittings leak with using Big Blue?

TRB on Mon July 25, 2011 11:18 AM

New bottles of both Red and Blue. No detection present.

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paulo57509 on Mon July 25, 2011 6:22 PM

I'm using Nylog blue.

The leak detector behavior is such that the "ticks" are slow and regular at first. Holding the probe close to the fitting the frequency of the ticks would increase. Pretty soon the detector will scream and the bar graph indicator will shoot up to max.

I'm sure it wasn't the burrito I had for lunch. HA

Here's the detector I use: http://www.otctools.com/products/electronic_leak_detector

Edited: Mon July 25, 2011 at 6:26 PM by paulo57509

TRB on Mon July 25, 2011 6:26 PM

I checked both Red and Blue lying the tip across the open bottle with a Yokagawa H10. Nothing at all.

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