Finding very slow AC leak

[Iciclehead]

Gentlemen and Ladies,

I just got the car out of storage, did its annual maintenance and found, to my chagrin, for the second year running, that the AC system was operating poorly, vent temperatures on the order of 60F, way worse than the 35F I have typically seen.

The system is a Retroaire and has worked well in general, but last year I had the same issue except for the system was completely empty of refrigerant.
I (last year) went and checked for visual leaks, found a very small amount of residue on the suction side of the compressor fitting, tightened the fitting as far as I dared and was able to draw and maintain vacuum.

All good, or so I thought. I recharged the system, had a good year with AC in last year's driving system and fully expected that all would be well....but, alas....no.

There is sufficient residual pressure in the system so that the compressor kicks in and provides some cooling, just not enough. I have checked all the fittings again for any residue of any kind (PAG oil leaks indicating refrigerant leaks), no problems.

So, the leak is very slow, taking over a year to lower the pressure this much.

How to find it? Any ideas of tackling a leak this slow? Or do I just charge it up and deal with having to put in a can of R134a every year?

How about adding sealant to the mix? Don't like the idea, but then again, I don't much like the idea of redoing every fitting, replacing the O rings and perhaps still not addressing the issue.

Thanks,

Dennis

PS - when I installed the system the first time I forgot to mount the Schrader fittings that RetroAire provided. Looks like there is no real way to put them on now unless I evacuate the system....mind you, I also don't know how to do that. I presume I have to take out the little valve assembly on the compressor inlet/outlet and then thread the Schrader's onto those.

[DaveMcKenz]

Hi Dennis,
That scenario is fairly common. Shrader valve leaks are pretty common, particularly with old cores. Very easy to change, depending on what adapters/cores you now have. I would recommend evacuating the system, removing the port adapters you have, removing the old cores and installing high quality adapters with new cores.
Do not under any circumstances put any sealer in the system. I will probably destroy your system and you or the next owner will need to start over again. Do a search of a/c black death.
You may need to have a pro do the charge adapter work, and he may be able to find your leak with electronic detectors, etc.
Good luck.
Dave

[wwest]

Originally Posted by Iciclehead

Gentlemen and Ladies,

I just got the car out of storage, did its annual maintenance and found, to my chagrin, for the second year running, that the AC system was operating poorly, vent temperatures on the order of 60F, way worse than the 35F I have typically seen.

The system is a Retroaire and has worked well in general, but last year I had the same issue except for the system was completely empty of refrigerant.
I (last year) went and checked for visual leaks, found a very small amount of residue on the suction side of the compressor fitting, tightened the fitting as far as I dared and was able to draw and maintain vacuum.

All good, or so I thought. I recharged the system, had a good year with AC in last year's driving system and fully expected that all would be well....but, alas....no.

There is sufficient residual pressure in the system so that the compressor kicks in and provides some cooling, just not enough. I have checked all the fittings again for any residue of any kind (PAG oil leaks indicating refrigerant leaks), no problems.

So, the leak is very slow, taking over a year to lower the pressure this much.

How to find it? Any ideas of tackling a leak this slow? Or do I just charge it up and deal with having to put in a can of R134a every year?

How about adding sealant to the mix? Don't like the idea, but then again, I don't much like the idea of redoing every fitting, replacing the O rings and perhaps still not addressing the issue.

Thanks,

Dennis

PS - when I installed the system the first time I forgot to mount the Schrader fittings that RetroAire provided. Looks like there is no real way to put them on now unless I evacuate the system....mind you, I also don't know how to do that. I presume I have to take out the little valve assembly on the compressor inlet/outlet and then thread the Schrader's onto those.

I would not normally advise this, but in your case..

You can buy R-134a manifold pressure adaptor/fittings that depress the existing valve stem. Also, you would then have a double valve system at each fitting in case you have a slow leaking R-12 valve.

Sounds as if you have fitted a pressure switch, assuming so what is the high pressure compressor cutout PSI ??

Anything more than 325 PSI would be inadviseable.

A 12 Oz (net, 8-9 Oz actual) can of R-134a Is an little as $7.....

Even if it takes 2-3 cans...

[Iciclehead]

Originally Posted by wwest

I would not normally advise this, but in your case..

You can buy R-134a manifold pressure adaptor/fittings that depress the existing valve stem. Also, you would then have a double valve system at each fitting in case you have a slow leaking R-12 valve.

Sounds as if you have fitted a pressure switch, assuming so what is the high pressure compressor cutout PSI ??

Anything more than 325 PSI would be inadviseable.

A 12 Oz (net, 8-9 Oz actual) can of R-134a Is an little as $7.....

Even if it takes 2-3 cans...

I will look for the adapters that depress the existing valve stem....if you have a source for those, please direct me to it.....it would definitely be a solution, particularly if I go down the route of just adding r134a.

There is a high pressure switch in the Retroaire system, don't know its settings, but when I hook up the gauge set my pressures were below that and within the tolerances.

The issue is you really cannot buy R134a as a consumer here in Canada. Now....it is available through alternate means...so I can definitely manage it. It may turn out to be the best solution.

Thanks for your help, I do appreciate it.

Dennis

[Iciclehead]

Originally Posted by DaveMcKenz

Hi Dennis,
That scenario is fairly common. Shrader valve leaks are pretty common, particularly with old cores. Very easy to change, depending on what adapters/cores you now have. I would recommend evacuating the system, removing the port adapters you have, removing the old cores and installing high quality adapters with new cores.
Do not under any circumstances put any sealer in the system. I will probably destroy your system and you or the next owner will need to start over again. Do a search of a/c black death.
You may need to have a pro do the charge adapter work, and he may be able to find your leak with electronic detectors, etc.
Good luck.
Dave

Thanks for the feedback, the sealer thing is definitely off of the list.. your advice and others I have read have convinced me entirely.

Issue is finding an AC shop here in Calgary that is willing to do custom work. Most of them take one look at the car, hear that I did the install myself and either quote stupid numbers (yes, we will charge it for $1500, no guarantees) or just tell me (literally) to get off of their property with my stupid little car.

No joy likely there, but perhaps I can try again...

Thanks for your help,

Dennis

[DaveMcKenz]

Sorry to hear how difficult it is to find an a.c. shop. It's not that bad to diy. Lots of information here.
Good luck
Dave

[uwanna]

To find the leak, you need to use an electronic "sniffer". They are not too expensive. I have had one for years and they are super sensitive.You just move the wand head around all the connectors and if even a tiny amount of R134 (R12 or any "halogen" type gas) is present the unit will beep like crazy. I have tested mine by checking in the vicinity of a disconnected guage set after recent use, and it went nuts. Perhaps a Pelican near you may have one you could borrow.

Electronic Freon and Halogen Leak Detector

[DaveMcKenz]

Be careful. I bought a cheap one and it responded to moisture.
Dave

[Lyle O]

Please forgive my complete ignorance on this topic, but could you just fill with a nice inert gas like nitrogen and squirt soapy water around all the fittings? (See, I told you I am ignorant on this...).

[uwanna]

Originally Posted by DaveMcKenz

Be careful. I bought a cheap one and it responded to moisture.
Dave

you're probably right, a cheap one is surely not the best idea. Only showed the HF one for a pic of what one looked like. I have a pricey good one, albeit I bought it cheaply from a pawn shop! Since the 2008 recession, many mechanics pawned their tools and never reclaimed them, ergo there are some really great deals
on tools at pawn shops! Quite a few of my very high quality tools came from a pawn shop, at less than HF prices!

[Bob Kontak]

Originally Posted by Lyle O

Please forgive my complete ignorance on this topic, but could you just fill with a nice inert gas like nitrogen and squirt soapy water around all the fittings? (See, I told you I am ignorant on this...).

Yes you can and I would like to know hot to set up the fittings to do this.

[fastfredracing]

Dye, and a dye light would be helpful here also. Won't really help if it is coming from the service ports though

[wwest]

Originally Posted by DaveMcKenz

Be careful. I bought a cheap one and it responded to moisture.
Dave

Moisture as in condensate droplets, liquid, or moisture as in vapor/fog..???

[darrin]

Originally Posted by Lyle O

Please forgive my complete ignorance on this topic, but could you just fill with a nice inert gas like nitrogen and squirt soapy water around all the fittings? (See, I told you I am ignorant on this...).

Expanding on Bob's comments above -- we did exactly this tracking down a pinhole leak in a vintage home refrigerator -- I believe we fed the nitrogen in through a standard 2 dial AC manifold using "normal" schrader fittings (it's been around 15 years now). interestingly, there's plenty of residual freon still left in the system, so even though it was pressurized with nitrogen, the freon detector still had no trouble finding the leak. A lot cheaper using nitrogen than r12/r134.

[DaveMcKenz]

Originally Posted by wwest

Moisture as in condensate droplets, liquid, or moisture as in vapor/fog..???

I once replaced an evaporator on a Bentley due to r134 leak, because the detector showed leak at vents when a/c turned on. After a while, I noticed it would detect a leak when put near my sweaty hands. I then took a cotton towel, moistened it with water, put that in front of a household fan. The detector went crazy from the humid air it blew. That leak detector was thrown away.
There are, however very good electronic leak detectors. Just not that one.
Dave

[db_cooper]

Originally Posted by darrin

Expanding on Bob's comments above -- we did exactly this tracking down a pinhole leak in a vintage home refrigerator -- I believe we fed the nitrogen in through a standard 2 dial AC manifold using "normal" schrader fittings (it's been around 15 years now). interestingly, there's plenty of residual freon still left in the system, so even though it was pressurized with nitrogen, the freon detector still had no trouble finding the leak. A lot cheaper using nitrogen than r12/r134.

Soapy water in a spray bottle works fine with 134a, R12 or Hc12a too..even if the system is partially discharged.

[DaveMcKenz]

Really db?
Soapy water works fine for a gross leak. For 12 oz. per year, it ain't goin' do it.
Sorry,
Dave

[T77911S]

go to an HVAC parts house and get their soapy water. it works better. has a "sticky" substance in it.

if your evap is leaking you really need a sniffer. i have one. found a leak on my rear condensor and in the line that runs down the left side of the car. leak was just in front of the rear wheel