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Evacuate and Charge procedures question

Anonymous on Wed June 30, 2004 5:20 PM User is offline

Great site!

On question though, on the Evacuate and Charging Procedure tip.

It says to hook up gauges, vacum, etc.. then "...Assuming the system is holding a vacuum after letting the moisture boil off repeat the evacuation procedure again. This process may need to be done a few times before all moisture has been removed and you see no degradation in vacuum after closing both dials for 5 to 10 minutes."

So, if you are holding at ~29.9hgs, meaning no big leaks, do you let air back into the system to 'repeat'? Or do I just run the vacum for another 30 minutes, even though it is already there at 29.9?

Thanks for the help..

Cussboy on Wed June 30, 2004 6:58 PM User is offline

No, do not let air back into the system for a "repeat". 30 minutes plus at 29" vacuum, after which the vacuum holds, should be sufficient. If you want to extra analytical, let it pull vacuum an hour.

ChemE on Sat April 12, 2008 9:54 PM User is offline

Evacuating a second time, probably means to add a little refrigerant, then pull vacuum again. My GM shop manual recommends triple evacuation. I think that is unnecessary.

If the system had a lot of moisture, though, the remaining gas after a single evacuation could be mostly water vapor. If you do not have a real strong vacuum pump, that could be a significant amount of moisture. In that case a second evacuation would help to get rid of it.

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