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can i put in positive pressure to find leak?

lv6l on Fri August 15, 2008 4:17 AM User is offline

I have my AC system out of the car and in my garage all hooked up. I vacuum it and at first it held pressure at -29. I left it there for about 4 hours. Checked and it was still good. Then I removed it and evacuated it again and it went back down to -10 within 30min. I was wondering can I shoot compress air into the AC system and spray water on the hoses to find leaks like how you would do it for a bicycle tire? Thanks.

NickD on Fri August 15, 2008 8:44 AM User is offline

Legal to dump in a can of R-134a.

HECAT on Fri August 15, 2008 8:45 AM User is offline

Caution, compressed air and R134a combined is flammable/explosive.
Caution, compressed air if not filtered properly can contaminate with air compressor oils and moisture.

OK, with the warnings out of the way, why not? Just don't apply more than about 100 PSI.



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lv6l on Fri August 15, 2008 3:15 PM User is offline

Sorry for not stating my questions more clearly. But let clear this up. I have my AC system out of the car and in my garage. It is all hooked up sitting in my garage. There is NO freon in there what so ever. When I put in compressed air I am not mixing it with freon. When I add in compressed air I have a filter on my compressor to separate the oils and fluid. And finally when I add compress air the high side does not go any higher than 50psi. Is this safe still and do you think it would be easy or hard to find a leak using this method. Thanks.

Edited: Fri August 15, 2008 at 3:16 PM by lv6l

mk378 on Fri August 15, 2008 3:20 PM User is offline

Yes that is safe. The main concern is water. But if you have a good filter, such as would be used for spraying paint, no problem. The drier would of course be replaced when you install the system back on the car in any case. I would put it back on the car with the old drier, leak test again, then replace the drier, evacuate and charge.

lv6l on Fri August 15, 2008 3:32 PM User is offline

Oh thank you for that information. What is your guy's opinion on my chances of finding the leak using this method.

mk378 on Fri August 15, 2008 3:41 PM User is offline

Fairly good, since everything is out in the open.

iceman2555 on Fri August 15, 2008 3:59 PM User is offlineView users profile

Finding a large leak.....perhaps....finding any other than that .....slim to none. Adding air to a system....in or out of the a vehicle is not a good test. Systems will leak refrigerant and not leak air.

The best method...simply shoot a can of 134a into the system.....static pressures will exceed those necessary to locate most leaks. Also the bubble test normally will work only with a significant size leak.

Air from a compressor is or can be heavily contaminated with moisture.....saturate the desiccant.....oil residue from the air pump.....some dirty stuff.....the 134a will work much better.

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

lv6l on Fri August 15, 2008 6:13 PM User is offline

Oh i see. So you're saying put in a bottle of r134a and how do I go and find the leak from there?

iceman2555 on Fri August 15, 2008 9:11 PM User is offlineView users profile

Your idea of soap....recommend the use of a child's bubble solution....it will not harm aluminum...some soaps will adversely affect aluminum parts.
But the best idea would be to use the correct tool.....a refrigerant leak detector......soap is simply not going to be as efficient as the correct tool.
However, if you lack the tool or the funds to acquire one.....put the system together....on the vehicle....add 1/4 oz of dye...evac and recharge.....operate for a week or two and check for evidence of dye/leaks.

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

lv6l on Fri August 15, 2008 11:01 PM User is offline

Can I add a bottle of freon that has dye in it to the system outside of the car and use a UV light to find the leak that way? Or does the system need to be circulated in the car in order for this to work. Also I am unsure if there is dye left overs from previous users so is there anything I can use to clean off and wipe down all the dirt, debris, old dye. Thanks.

NickD on Sat August 16, 2008 7:39 AM User is offline

Legal to dump in a can of R-134a. But that is after drawing a vacuum, should have added that, but assumed it was obvious, not very easy to add R-134a to a system loaded with air and yes can buy a can of it with dye.

lv6l on Sat August 16, 2008 3:44 PM User is offline

Quote
Originally posted by: NickD
Legal to dump in a can of R-134a. But that is after drawing a vacuum, should have added that, but assumed it was obvious, not very easy to add R-134a to a system loaded with air and yes can buy a can of it with dye.

Sorry but I have no clue what you just said. That did not even answer my question.

But I decided to take the advice by putting in freon with dye and run it in my car for a weak and use a UV light to locate the leak. Problem is now. What do I use to safely clean off all old dye off my lines.

iceman2555 on Sat August 16, 2008 5:33 PM User is offlineView users profile

There are dye cleaners available...work very well...also PupleStuff, Simple Green, and other cleaners like this seem to work well. You are correct in cleaning the residuals from previous owners....
The dye should be used in an operational system to insure that all components are introduced to the chemical. Simply dumping into a static system...either on the vehicle or in a condition as yours will not give a true indication of potential areas of leakage.
Lubricant is available with dye...but personal preference is the small liquid container. 1/4 oz is sufficient for most all systems.
Good luck!!!

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

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