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jjrbus
User
Jul 4, 2015, 7:41 AM
Post #1 of 16
(2133 views)
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El Cheapo manifold set
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I vacuumed the system and it seemed to be holding, but did not last overnight. Having a suspicion I tested my cheaper than Harbor freight manifold set and it does not hold a vacuum on its own! Shoulda known better, now what to do?? Jim
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 4, 2015, 9:56 AM
Post #2 of 16
(2126 views)
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Re: El Cheapo manifold set
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Some manifold set's "parking" spot for the connectors are NOT sealed to check gauges so you have to make up plugs to test the set. It should still vacuum against the shut offs before the connectors and show max vacuum fast. If none of that works take them back as NG. You shouldn't have to fix new even cheap stuff and some OK for low use.
FYI - making plugs. Takes a couple more bucks to get retrofit adaptors with same threaded ends for R-12 cars which is plumbing threaded. Then hardware stores will sell plugs for those fittings threaded ends or some auto parts would have also.
Don't expect parts outlets to know what you want. Be sure lower cost set does read vacuum on low side gauge - some don't! Super cheap, like $35US good for spare hoses only really in a jam IMO.
Ask about rentals too, some free with full deposit. If you can't trust holding a vacuum over manifold set you'll never know if a system is holding and can't proceed.
Know that just a system holding vacuum isn't proof it will hold pressure but a must before continuing,
T
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Hammer Time
Ultimate Carjunky
/ Moderator
Jul 4, 2015, 10:17 AM
Post #3 of 16
(2122 views)
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Re: El Cheapo manifold set
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All it means is that you can't rely on a vacuum reading to check for leaks. You can still use them as long as you don't waste any time between vacuum and charging. You probably should invest in a better set of gauges. I wouldn't expect them to be too accurate either.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 4, 2015, 11:30 AM
Post #4 of 16
(2114 views)
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Re: El Cheapo manifold set
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Yes - Jim - If you can pull a full vacuum that will hold for even a short time it might be just fine. Overnight is a long time. IDK what all others consider enough but I say ~30 minutes and know some don't wait that long.
Perhaps get it to max possible for your altitude and then leave it in a state of pressure with a known amount of refrigerant and see if that # stays true for an overnight according to the temperature totally considered. Don't confuse a lower static pressure overnight with a leak as it would be cooler. Chart above locked can help. If pressure later is lower in PSI than the temp in Fahrenheit (must know exactly) suspect a leak or empty if you left it with a few ounces of refrigerant and credible when left earlier,
T
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jjrbus
User
Jul 5, 2015, 8:43 AM
Post #5 of 16
(2092 views)
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Re: El Cheapo manifold set
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Hey Guy's thanks for the responses. I twiddled and tweaked and fiddled with this set and can get it to hold a vacuum, but not consistently.
I played with it and noticed that it quickly reach's 29 on the 0 to 30 scale, quickly less than a minute and will hold that for 30 minutes.
When I said this was a cheap set it was $27 with free shipping on Ebay. I should have known better, but all I wanted to do is vacuum the system down and check for leaks before installing new parts in engine area, then take it for charging. However this is becoming interesting and I may try to charge it myself.
Many thanks Jim
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 5, 2015, 9:50 AM
Post #6 of 16
(2089 views)
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Re: El Cheapo manifold set
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If you trust 29Hg is really that at some altitude* fine. Remember this is the final step before charging. As a leak finder it isn't just can prove it's not tight somewhere unknown. A full vacuum is considered ZERO anything but oil left in system hence really only blocking or keeping OUT 14.7 +/- PSI of atmospheric pressure not holding the possible 300+ PSI of an A/C gas so not proof just a stopper if it can't.
Leak finding is it's own thing.
* Altitude! It does matter to some depending on where you are for elevation both vacuum Hg and atmospheric pressure is different. No atmosphere or pressure at so many miles high where you couldn't be working..........
T
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jjrbus
User
Jul 11, 2015, 7:07 AM
Post #7 of 16
(2059 views)
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Re: El Cheapo manifold set
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Me again! I went to AutoZone and rented a set of gauges, tested them on their own and they hold vacuum. Tried on vehicle and at 30 minutes it is, did that gauge move or not?? It may have moved a bit, but not sure. At one hour on the 0-30 scale it was about 26.
It was suggested I pressurize system with compressed air. My compressor is old and has no filters, so it seems like it would contaminate the system.
I am befuddled and not sure what to do. I can take it into a shop where they can test it, or just charge it and hope for the best?
What would be my best course of action? Jim SW FL
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Discretesignals
Ultimate Carjunky
/ Moderator
Jul 11, 2015, 7:53 AM
Post #8 of 16
(2056 views)
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Re: El Cheapo manifold set
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I wouldn't use shop air to pressure check an ac system. Shop air has moisture in it that will contaminate your refrigerant oil. If you were to pressurize it with nitrogen, that would be acceptable.
I think your going to be ok to go ahead and charge the system. As long as it doesn't drop to zero after sitting several hours or overnight, you'll be fine.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jul 11, 2015, 7:54 AM)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 11, 2015, 8:29 AM
Post #9 of 16
(2050 views)
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Re: El Cheapo manifold set
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Some questions on this: Did whatever vacuum pump even pull 30? Just not stay there or what? You should be able to vacuum just the gauges without a vehicle to know capability or accuracy THEN on to a vehicle.
Again ave. Atmospheric pressure is just a hair under 14.7 PSI such that in vacuum on perfect day at sea level could only max out to 29.92 Hg. Make room for minute adjustments for weather and lots for altitude. Sorry - SW FL last I checked unless you are doing this in a helicopter doubt has more than 25 feet of elevation - check but whole state isn't a mountain where it really matters.
So - do you believe 26 Hg that holds? Truth is it would work but wouldn't be professional to quit seeing that.
Leak checking is an art and can be elusive as all get out. No shop air please as DS said. Nitrogen w a tad of R-22 will leak thru smaller leaks where air or nitrogen alone might not. Case of molecule size - really!
The whole game is what you do and pay attention to will give you the best chance for a lasting fix without contaminating products that can become corrosive and end it for A/C for vehicles not worth that much work.
Again, paying attention pays off. Bad info from equipment is a real bummer,
T
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jjrbus
User
Jul 11, 2015, 1:01 PM
Post #10 of 16
(2042 views)
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Re: El Cheapo manifold set
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Hey guys thanks for the response!
I am on a big hill here in N Ft Myers so I am at 7 feet of elevation :)
I did check the AutoZone gauge before and after I tested the system and it does not lose vacuum.
Did the gauge hold 29 exactly, my eyes are not that good, I would have had to use a magnifying glass.
I watched the gauge after I posted and it very slowly dropped, I do not believe it would hold over night.
So now I am looking at way to pressure test or maybe take to shop to have done. My experience in FL with shops has been very bad and I will avoid going to one. Plus if I take to shop I do not learn anything.
Jim
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Discretesignals
Ultimate Carjunky
/ Moderator
Jul 12, 2015, 11:24 AM
Post #11 of 16
(2029 views)
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Re: El Cheapo manifold set
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Most shops will probably charge it and look for leaks with either an electronic leak detector or they will shoot it with dye. Question them on that because you can do the dye thing yourself. If you or a shop can pressurize the system with nitrogen, you or they could use soapy water or a ultrasonic leak detector to locate a leak unless it was in the evaporator or expansion valve. Don't let any shop try to inject a sealer in the system!
Another trick is to separate parts of the system. For example: If you think there is a leak in the evaporator, disconnect one of the lines at the firewall and then one at the compressor or line connection near a service port. Then get a set of these colored rubber plugs to shove in the end of the lines. Put a vacuum in and see if it stays. I actually do that if I suspect an evaporator leak on something you have to rip the dash out of sometimes. You can also reverse your procedure and disconnect both lines at the firewall and plug those to see if there is a leak on the front side of the system. It is just a way to isolate a suspect leak in the system.
Of course, sometimes things won't leak with a vacuum applied, but will leak under pressure. I've also ran into some compressors, such as an A6 compressor, that will leak out the front seal when a vacuum is on it, but seals when pressure is against it. Just FYI.
vacuum plugs
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jul 12, 2015, 11:34 AM)
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jjrbus
User
Jul 12, 2015, 1:28 PM
Post #12 of 16
(2015 views)
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Re: El Cheapo manifold set
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Hey great ideas!
I am after this on a two prong approach. One I am asking around trying to find a trustable AC guy, I know they must be out there. 2. I am looking for nitrogen to do a leak test with, I cannot spend $500 on a nitrogen setup, but may be able to jury rig something? At the moment I am hampered, I have done the water pump, timing belt, radiator etc and am not mobile yet.
Thanks Jim
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 12, 2015, 2:31 PM
Post #13 of 16
(2013 views)
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Re: El Cheapo manifold set
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If you don't have a "sniffer" for leaks than if not visible as an oil or dye leak now you'll need help. They don't rent electronic leak sniffers (I call them) out for good reasons as it would be wrecked too easily IMO.
If at a connection bubble test does work with some pressure especially refrigerant. Compressor shaft seals show oily evidence that's fresher looking if it was working recently.
Leaks you can hear need no comment.
Other trick: For suspect evap and little for tools check for an oily mess where condensate (water) would have been dripping out - should be none just road dust if anything,
T
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jjrbus
User
Jul 12, 2015, 3:10 PM
Post #14 of 16
(2010 views)
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Re: El Cheapo manifold set
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This system is all brand new, never had gas in it or pressure. The leak is miniscule so not able to hear, an ultrasonic detector might pick it up, but I do not have one of those. I may have reached the practical limits of DIY?
Jim
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 12, 2015, 3:46 PM
Post #15 of 16
(2007 views)
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Re: El Cheapo manifold set
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Constant issue is when OWNING tools and equipment could NEVER pay off it isn't worth it. Gee - I'd love to own a backhoe to pull a stump out vs paying someone - do the math ya know?
You can do and enjoy doing lots of things that don't run you broke to have tools for that are also useful to have anyway. Think what you'll never touch again or will be broken if you even did type stuff that costs a fortune it isn't worth it never mind the room to store it.
So if you are there the next thing is to find help for the part of the whole job you really can't justify doing yourself or own tools for and quite possibly not for leak finding for A/C.
Think I said it's not always easy with all equipment known. Could be totally a hide-n-seek game. What if the sucker holds pressure but not a vacuum? What if there is more than one leak? It might not leak when tested and really cause hair loss then what? I say it helps to find a tech/person who has done it, seen it and the exceptions for one step like this that you may never encounter again. There are plenty of things the smart way is to send something out for all or part of the fix,
T
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Discretesignals
Ultimate Carjunky
/ Moderator
Aug 8, 2015, 3:05 PM
Post #16 of 16
(1911 views)
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Re: El Cheapo manifold set
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Question answered and OP seems satisfied.
Thread closed as solved and continues on this page:
http://autoforums.carjunky.com/...s_F8/Update_P173855/
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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