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Does anyone know how to "evacuate" a/c?


Pete112's Avatar
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04-15-05, 11:55 AM   #1  
Does anyone know how to "evacuate" a/c?

Hi everyone,

I just installed a new compressor, new drier, and new evaporator in my '97 Acura CL. The guy I got the compressor from said that I must "evacuate" the entire system before adding R134. I'm a pretty good Diyer and I do realize this means to essentially purge everything out of the sytem, but does anyone know the steps on how to do this? Is it possible to do this without an A/C vaccuum? Are there some tools that I can rent or buy to get the job done at home?

Any help is greatly appreciated, as I would hate to do the entire job just to take it to a mechanic to get flushed/charged.

 
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jeffk's Avatar
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04-15-05, 12:29 PM   #2  
The pro's have a selfcontained vacuumpump/charging unit where the gas sucked out is contained in a cylinder. Harbor Freight has a cheap ($15) air powered vacuum pump. Vacuuming the system (perfect or near vacuum) draws out all the moisture which can plug up the system and thats why its done.

 
Ed Imeduc's Avatar
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04-15-05, 12:58 PM   #3  
Yes for sure you want to put a vauucm pump on it. First the pump will like cook any and all the moisture out of the system that is one of the main things .Then the pump will pull any air out of the system. You cant have any of that in the system as it is contaminate or noncondensable. It pays to like break the vacuum with some 134 and pull it down again before charge. Also be sure and blow the hoses out with 134 so there is no air in them before you put them on the AC unit.

Harbor Freight has a cheap ($15) air powered vacuum pump.
This pump wont start to do what you need here for the job

ED

 
Pete112's Avatar
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04-15-05, 01:41 PM   #4  
Thanks guys for getting back so quick.. So, you mean I shouldn't bother purchasing a cheap vaccuum pump because its not going to do the job? That basically means I have no choice but to bring it in to a shop?

 
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04-15-05, 02:59 PM   #5  
Purchase a new ROBINAIRE pump on eB*y for 150 bux, mine has been goin strong for 8 yers now.

 
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04-16-05, 05:45 AM   #6  
Unless you're going to be doing ac work frequently, just take it to a good shop and have them evac and service it.

Side note [and DON'T TRY THIS AT HOME]. When I was young and poor the compressor crapped in our '76 Corolla. This was back in the R-12 days when you could buy cans of R-12 and a can tapper hose. I got a used compressor and a new drier and installed them. Then to evac the system I rigged up a section of hose to a screw-on tire valve adapter and sucked the sytem down using......engine vacuum. Yep, hooked up to a vacuum source on the engine and fired it up. Let it run for 5 minutes or so and then unscrewed the adapter and put the freon in. Don't laugh; it worked surprising well and the system cooled just fine. Again, DON'T DO THIS.


Measure it with a micrometer; cut it with an ax.

 
Kestas's Avatar
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04-16-05, 07:02 AM   #7  
Another trick for DIYers is to salvage a compressor from an old refrigerator or dehumidifier and use that as a vacuum pump.

 
Ed Imeduc's Avatar
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04-16-05, 08:14 AM   #8  
Dont think any of the above can get the vacuum down to 15 to 25 microns so you have all the moisture out.

ED


Last edited by Ed Imeduc; 04-16-05 at 10:09 AM.
 
Pete112's Avatar
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04-18-05, 12:47 PM   #9  
Once again, thanks everyone! I found someone in my area that was recommended from another shop. He said he'll do the whole evacuate/recharge for $75. I hate paying shops but I already saved money on installing the evaporator and compressor myself. Guess you should bite the bullet sometimes. Seems like if I try myself it might end up breaking again in the near future.

 
Kestas's Avatar
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04-18-05, 12:51 PM   #10  
UV dye

Have him put some UV dye in the system before evacuating...... just in case. It's good form for a mechanic to put UV dye in the system during any repair.

 
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