[AT] Air conditioning problems In my parts getter...

[Cecil Bearden]

In the 55 years that I have worked on Mobile air systems, I have had 
several that would hold vacuum and not pressure.  I checked into a NH3 
detector, but the price is a little high for me right now.  The main 
leak I have is in the New Belarus.  I think the problem started when it 
was split and a splice was put in the hose under the cab.  It needs a 
sealing connector in it.  It also was not vacuumed out when it was 
recharged after the split.  I used the compressor side vacuum to pull a 
vacuum and should have held a vacuum for 30 minutes to get all the 
moisture out...
Cecil

On 6/11/2021 9:03 PM, Steve W. wrote:
> Brad Loomis wrote:
>> In the trade one always uses nitrogen. Co2 has moisture, bad in 
>> sealed systems. Of course you're supposed to evacuate to <500 microns 
>> but...
>> I once had a13oz. R-12 system that I never found the leak. From 
>> 150psi nitrogen to my brand new, then, Inficon leak detector. Check 
>> your Schraders after you put the caps back on. You may be surprised. 
>> Why I preferred leak finding after I moved to NH3. Easy, save for 
>> having to cut the skin off a double stainless jacketed 155,000 gallon 
>> tank. But the leaks were always in the same areas. Brad
>>
>
> Depends on the shop, I know of some that use shop air! I've had a few 
> leaks that didn't show up under system pressures in operation, but 
> once equalized from setting overnight you would find a bad seal or 
> O-ring that wasn't seated quite right. Had one that would leak under 
> pressure but would hold a vacuum forever, that was a piece of rust 
> that acted like a check valve!
>