Air con acceptable leak rate?

[Smithy111]

Traced a major leak in my a/c system to a holed low side hose and have cut and repaired the section. I know it’s not strictly the correct way to test a system but I’ve managed to push 45psi into the system via the low side port and it’s only lost 5psi in an hour. Is that good?

[Escape]

A good system should have no leaks at all. Losing 5psi in an hour is quite a lot, you wouldn't be able to to run it for long without needing to refill it. Do you think you've lost the pressure through the repaired section, or is going elsewhere? Maybe filling through the low side didn't get much in the high side, and what you're seeing is pressure equalising between the two. 

[Smithy111]

Good point, maybe i need to put pressure in the high side as well, its bloody awkward to get to the ports on the back of the compressor when its been fitted upside down! Will get a dye kit as well and see if anything shows up. The whole system is original except the compressor so was expecting more leakage than im getting.

Does anyone know the acceptable pressure loss and over what time? I assume there is some sort of standardised specification?

[910Esprit]

No - you must always charge low side  5psi an hour is a massive leak (relatively speaking).    Dye is useful, helped me find a leaking union.    If you still have original hoses. I'd be tempted to change them all, as R134 has a smaller molecule size and apparently can leak through old R12 hoses  (are you using R134?)

I would have thought 5psi per year would be nearer the original spec!    

[philcool]

The best way of testing a Cars A/C for integrity is by a vacuum test 

Vac the high and low side down to 2 Torr and isolate from the vac pump and see if it rises.

If it doesn't rise in an hour then your proberbly ok 

At 5psi an hour with a 45psi test  I give it a week before it's all gone 

The trouble is they hold such little charge 700g being the average for car A/C and as mentioned the old hoses can become porous and just leach out refrigerant .

If I test with nitrogen up to about 10 bar / 145 psi I expect the pressure to rise slightly on a good system as the expanded nitrogen from the cylinder is cold when entering the system and on a warm day will expand thus raising the pressure in the system by a PSI or so 

My friends Mercedes kept loosing it's charge about every month so tested and eventually found the condenser was just weeping on one of the fins took ages to find but without dye would never have found it 

[ramjet]

My S4 has a leak somewhere which showed up via a vacuum test. The pump would pull it down and then all of a sudden the reading would jump up, then the pump would pull a vacuum again and then just when it was about what the aircon guy wanted, boom, back out again.

I was going to suggest a vacuum test to check the system, not a positive pressure test.

Have used dye on the system, but have been unable to locate the leak. I was thinking that the only way may be to isolate each component and test each piece.

Have never got around to it and probably won't now as I am getting it ready to sell.

[Smithy111]

I’m going to try with soapy water spray on the joints and hoses first then if nothing else get some dye and air pressure in. If its tight after that then I’ll take it to be vacuumed out, replace the receiver drier and re-gas with the good stuff. ‘Taps nose’

[gregs24]

My Elise would pass a vacuum test, but only last a couple of months of use after a re-gas. Pipes were failing but I sold it before they went completely

[910Esprit]

1 hour ago, Smithy111 said:

re-gas with the good stuff.

Even more reason to make sure you dont waste it!

[Smithy111]

Further to this topic, the high and low side ports are very inaccessible on the back of the compressor (compressor upside down doesn't help) can i remove the quick connect conversion bayonet fittings and screw the diagnostic hoses directly to the compressor as a permanent thing and then move the ports to the rear of the engine bay where they would easily accessed and just p clip the hoses? i cant see any reason why not except that you would waste a very small amount of extra refrigerant that would fill the hose extensions?

[Smithy111]

I’m thinking of recharging the system myself as it is with fresh ether oil, uv dye and this https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F372684217332 in an effort to find the leak by running the system. I’ve checked as much of the hoses, connections and condenser that are accessible and can’t find anything using the bubbles method.

if I can find and repair it then have the system evacuated and recharged correctly. Maybe with a sealant as well?

opinions on this? I really need to fix this as it’s bugged the hell out of me since I bought the car

[910Esprit]

Would another option be to take it to  a professional who should have far better leak detection equipment, then you could opt to do the remedial work yourself once a leak is detected?

[Smithy111]

perhaps but where or who do I use, I won’t just pick someone out without a recommendation also it’s not the easiest car/system and I’m sure some won’t want to try

[910Esprit]

I wonder how good these are?  

https://www.ebay.co.uk/itm/Car-Air-Gas-Leak-Detector-Halogen-Tool-CFC-AC-Freon-Refrigerant-Leak-Sniffer/113866128097?hash=item1a82f33ae1:g:hVgAAOSw-HxdFyFC

[Chillidoggy]

I had my system pressurised, green dye added, ran it, and still no sign anywhere of the leak.

When I dropped the radpack, all the green dye was revealed, soaked up into the accumulated shite which had effectively rotted the alloy condensers. There was no way I could see any of this without dropping the pack.

[Smithy111]

Thats a pretty big leak! think ill have to get mine diagnosed and rule out as much as i can to start with, im guessing the condenser isnt going to be in great shape after 35 years! I did however find this bit of bodging under the dash which looks more than a little suspect!

[910Esprit]

If you mean the black tar goo - that's standard & correct!   I assume its some kind of anti-condensation 'stuff'

[Chillidoggy]

As Steve says, that ‘orrible black jollop, is standard, and exactly the same stuff as on my car.

I think you’re gonna have to bite the bullet and drop the rad pack, Chris.

[Dan E]

Never had that issue 

[Smithy111]

Wow im amazed thats standard even for Lotus there must have been a better way to do it?! I was going to chip it all off as i think it covered the expansion valve as well by the look of it! Guess it could still be leaking under all that crap. The hoses are also in a pretty bad way so i think its most likely the condenser and or hoses. Not sure i care enough about air con to drop the rad pack and replace the very expensive condenser unless theres an alternative fit item?

[Chillidoggy]

Thing is, if your condenser arrangement is anything like mine, the accumulated crap trapped between them will not only rot the condenser, but also block airflow to the coolant radiator behind it. If you look at my photo, a good percentage of the cooling capacity of my coolant rad was effectively blocked.

 As to whether there’s an alternative item, maybe @swindon_alancould help?

[910Esprit]

@Andyww identified a replacement condensor I believe   I've still got the orignal 35yo unit, which is working well.

I removed all the black goo while replacing my hoses, it peeled off easier than it looks.   It doesn't seem to have caused any issues.   It mainly covers a massive flare fitting, which also steps down the hose size. its pretty much an obsolete fitting that requires a revised solution if you replace it - I used a combination of a new flare fitting and an inline reducer to get where I needed

Edited October 21, 2019 by 910Esprit

[Chillidoggy]

14 hours ago, Dan E said:

Never had that issue 

Good job you're a cool character, then.

 

[swindon_alan]

4 hours ago, Chillidoggy said:

As to whether there’s an alternative item, maybe @swindon_alancould help?

Everything I/we know about air con condensors is here, although I don't think I have ever looked at the earlier original single condensors. Are there any labels or idents on yours? Unless someone else has or a spare that we can get something off? As above:

@Andyww identified a replacement condensor I believe

...which I would be interested to know for the cross reference section.

[Andyww]

The black stuff is completely standard on all ac systems not only in cars. It prevents condensation and water dripping on the carpet. Having said that in the UK this is not going to be a big issue as the amount of use it will get will likely not be enough to cause actual drips of condensation.

The original single condensor and evaporators on the Esprit seem to be bespoke units. They are heavy units made of brass. They look like industrial fridge plant parts rather than car items. One area of these cars Lotus didnt skimp on was the A/C.

I think I have mentioned before when I bought a Turbo Esprit in 1984 with its original R12 gas it would chuck out air at below freezing point!