whats the purpose of pulling a vaccum on the a/c system other than making sure it doesnt leak?

ive read about it boiling any water in the system out. But will there be water in a freshly cleaned and assembled system.

are there any other reasons to pull a vaccum?

 

You pull a vacume primarily for removal of moister the longer you pull the vacume the better all the way around. On a system that has been exposed to the eliments for an extended amount of time requires longer vacume but if you just exposed the system for repaires you may need from 15min to 30min and for a system that has been open longer maybe around 30min to an hour.

 

Good answer ^^^

Evacuation also removes air (a non condensable gas). Although you can see a leak if you lose vacuum, it isn't actually used to verify the system integrity. There are places that will leak under pressure but not under vacuum, so it's not really good for "leak testing".

 

Best answer^^^. I found out the hard way. Pulled a vacuum, didn't lose any vacuum for 2 hours, charged the system...found a leak

 

well thankyou so much for all the info, i was able to charge my system and it was nice and cold. Did you catch the key word? WAS....for about five minutes. Turns out the p/o mounted two extra tranny coolers and one of which has rubbed its way through one of the condenser coils. Worked for about five minutes nice and cold then,...pissssssssss. that sucks. At least my boneyard compressor is good and everything else worked good.

Question,....is a condensor coil able to be welded or brazed? Its pretty easy to get to since its on the side of the condenser? or do you think i should go for a used one? New condenser goes for about $149 at autozone or i
may be able to get a used one for free from a buddy's parts truck.

Last question. Those dang 134a update fittings...low pressure side when screwed on tight, its own valve core extension i guess pushes on the old one and wants to let pressure out. theres no actual seal on the valve core on the update fitting, Its more like just an extension. Should i back out the valve core extension until it stops contacting the valve core on the acumulator, when its not being pushed?(i hope your not confused)
The high side had no valve core or extension in it so i left the old r-12 valve core in and put the 134a fitting on over it. Is that right?(i hope you're not confused again.

sorry about the long post i guess i have a lot of things to tell and ask about.
Thanks again

 

OK first off CONGRATS and Im Sorry , Ok as far as your coil goes Yes It can I have sent some off to the radiator shop down the road, and they work wonders. As far as your fitting question, good job you did it right.
Just keep in mind if it works the first time then its not a ford lol.