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AC Leak -- Does mechanic know best?

Old 09-20-2018, 08:04 PM
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AC Leak -- Does mechanic know best?

Hi all. I have recently retrofitted my AC system with a sanden(-ish) 508 compressor. I have never had working AC in this car and the system was already empty. I installed all new suction & discharge hoses, condenser, accumulator/drier, orifice tube, and orings. Did not replace evaporator core or liqid line. New mineral oil.
I brought my car to a shop to get an r12 charge, and it would not hold vacuum. Mechanic says it was gone in 3 minutes.
I can have him diagnose it next week with a leak detector, but he says he would use r134 to get it in the system for cost reasons. Says this wont be a problem with the mineral oil or r12 because it will all be vacuumed out anyway. Says he's done it before no problem.
Any input there?
Also concerned the leak detector will add extra oil to the system? Should this even be a concern of mine?
Let's just say in the time I've owned this car I have become more than a little skeptical of anything mechanics tell me. Once burned, twice shy. Or, more accurately, 6 or 7 times burned...
Kind of hoping there is something easy I can do before next week to fix the leak, like change the schrader valve in the liquid line. But with the way my luck is going with this project (started over 2 months ago), I am losing optimism. I have invested a lot of time and some money in this project and would hate for it all to go to waste.
Thanks for reading.
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Old 09-20-2018, 08:17 PM
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Re: AC Leak -- Does mechanic know best?

r134 is not compatible with mineral oil and you cant vacuum it out. It needs to be flushed very carefully. I did a lot of research on this lately, will get link to the post

https://www.thirdgen.org/forums/tech...ml#post6243605
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Old 09-22-2018, 12:18 AM
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Re: AC Leak -- Does mechanic know best?

Originally Posted by LiquidBlue View Post
r134 is not compatible with mineral oil and you cant vacuum it out. It needs to be flushed very carefully. I did a lot of research on this lately, will get link to the post

https://www.thirdgen.org/forums/tech...ml#post6243605
Thanks, I'll look thru all that
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Old 09-22-2018, 09:34 AM
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Re: AC Leak -- Does mechanic know best?

r134 is not compatible with mineral oil and you cant vacuum it out. It needs to be flushed very carefully.
Absolutely true, all 3 points. It's an either/or situation, from the get-go; no mixing allowed. You make the system clean down to bare metal and rubber, decide what refrigerant you will use, and install accordingly. Once that is done there's no going back without cleaning it out all the way back down to the bare metal again.

I would suggest checking for leaks with compressed air and soap bubbles. Schrader valves make that a no-brainer. If it loses vacuum in 3 minutes, the leak(s) won't be hard to spot. You'll probably hear them.

If you didn't put the right oil into the compressor and accumulator before you installed them, you need to open the system back up anyway and do that; AFTER the leaks are found and repaired.

Do NOT put 12 back in it. Sure, it's a bit more efficient (better at refrigerating) than 134A, but the next time it leaks - and there WILL be a nest time, there ALWAYS is, sooner or later - you will just have to go back and re-re-visit all this yet again. Use 134A so that it's maintainable, and find other minor simple tweeeeks to improve the efficiency, like insulating the metal parts and the evap housing, for example. Advanced Search this forum for my userID and the phrase "orifice tube" going all the way back to the beginning of time to learn how to set it up properly.
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Old 09-22-2018, 10:19 AM
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Re: AC Leak -- Does mechanic know best?

Originally Posted by sofakingdom View Post
I would suggest checking for leaks with compressed air and soap bubbles. Schrader valves make that a no-brainer. If it loses vacuum in 3 minutes, the leak(s) won't be hard to spot. You'll probably hear them.
I will read thru your old posts, thank you. And a compressor I can do. Does one of your posts descibe this? Whats the best entry point?
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Old 09-22-2018, 10:30 AM
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Re: AC Leak -- Does mechanic know best?

I think the reason a lot of people complain about r134 conversions is because they don't do them correctly. If you do everything to the letter, my hunch is r134 will be good. I know my r134 cars that are newer work great. If you really want to take it far, and don't care about staying with parts from the era, you can replace condenser and compressor with modern technology and it will likely be as good as anything.
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Old 09-22-2018, 11:08 AM
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Re: AC Leak -- Does mechanic know best?

To test an A/C system with compressed air, fill it, douse it with soapy water, and watch for bubbles. Make sure you use clean, dry, oil-free air.

You can put the air in through the Schrader valves. Just like filling a tire. Same air chuck and everything.

Don't outsmart yourself here. it's REEEEEEEL EEEEEEZY.
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Old 09-22-2018, 11:34 AM
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Re: AC Leak -- Does mechanic know best?

Originally Posted by sofakingdom View Post
To test an A/C system with compressed air, fill it, douse it with soapy water, and watch for bubbles. Make sure you use clean, dry, oil-free air.

You can put the air in through the Schrader valves. Just like filling a tire. Same air chuck and everything.

Don't outsmart yourself here. it's REEEEEEEL EEEEEEZY.
Otay! I am determined to get this right. Thanks again. I'll show all these mechanics trying to do me dirty.
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Old 09-23-2018, 08:52 AM
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Re: AC Leak -- Does mechanic know best?

Originally Posted by i88aGT View Post
Otay! I am determined to get this right. Thanks again. I'll show all these mechanics trying to do me dirty.
It may be an honest mistake on their part. Maybe he's just not an A/C guy and who sees R12 these days? From my research - "Analysis of DENSO A/C Compressor warranty claims show that in a quarter of all cases garages did not use the correct PAG-oil that is needed for DENSO Compressors" And that is just the ones that bothered trying to warranty it.
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Old 09-25-2018, 08:22 AM
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Re: AC Leak -- Does mechanic know best?

if your replacing all this why not convert to 134? I don't think you could ever tell the difference I've had several systems converted no sense using outdated HIGH priced Freon, do it once and your done no need to look back
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Old 09-25-2018, 06:16 PM
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Re: AC Leak -- Does mechanic know best?

Try pull a vacuum and see if you can hear where the leak is coming from. I wa able to tell I had a bad seal at the compressor when I did mine...especially if yours won't hold a vacuum for more than 3 minutes
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Old 09-26-2018, 03:37 PM
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Re: AC Leak -- Does mechanic know best?

Thank you for all the advice and replies. I will be updating again shortly.
I 100% agree with everyone, convert to r134. There isn't an easy r12 conversion as I mistakenly believed. I based a lot of my decisions and part orders on a certain timetable and particular compressor I thought would be ideal and turned out to be not as advertised. A series of falsely advertised parts, backorders, and my goofy install order backed me into a corner with r12.
For the record, everyone, just get the flex 7 or 7 piston sanden for r134. Get the bracket kit and oring from Original Air (I did not like the ones I got from Vintage Air-- they were incomplete).
The compressor I ordered was advertised as a 508 sanden r12 with 6 rib pully and mineral oil. I even had an email correspondence with the company beforehand to make sure this was true. Came shipped with PAG OIL. So disappointing and infuriating, especially after delays. And completely outrageous that this American company with "custom" "American" parts and fake patriotism on their website has parts shipped directly from China, to the point where they don't even know what's in the boxes of what they're selling (yeah they had the nerve to email me that it wasn't their compressor because they didn't even recognize it, until they realized they were wrong). At that time I should have returned it and started over with plans for r134, but I decided to make it work because I had already installed all of my other parts (none of which were easy installs for me) and my project was so far behind.
And if this compressor turns out to be the problem I am going to be so flipping mad...
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Old 09-26-2018, 04:33 PM
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Re: AC Leak -- Does mechanic know best?

If your compressor is still working, you can probably use it. Just need to drain oil and put proper oil in it. I'd flush it a few times with oil you are going to use, or an a/c oil that acts as a flushing agent and then again flush it a few times with the oil you are going to use. See my posts concerning this on the link above in this thread. I never confirmed if there is such a flushing oil, but it appears to be mentioned. You got nothing to lose other than the compressor that you don't like anyway! Well, almost nothing, if it burns up, then you'll need to flush your system again to get potential metal shavings out of system. Newer style condenser may need replaced, I read they can't be flushed very easy.
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Old 09-28-2018, 10:26 PM
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Re: AC Leak -- Does mechanic know best?

Yeeeeaaaaah! It works! I'm so happy! Thank you everyone for the replies, for all the links and search suggestions, I read them all and I got it done. New schrader valves, different oring at the accumulator (I had the wrong size, I believe) and reattached everything to doublecheck. No leak. New pressure switch at the accumulator because the old one was bad. Charged with r12 and it is so, so cold. It's great.
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