Another dumb question

[Kw9006nz]

(06-16-2021 )Chamberpains Wrote:  Your vacuum should hold 27ish-30 in/hg (depending how good the Guage is that your using) indefinitely. 30 min is just the least amount of time you want to leave it hold to check for leaks.

Quick ? For you what vac pump do you have? my pneumatic vac can only pull 20-26 depending on weather!

[Chamberpains]

I have something like this. https://www.amazon.com/dp/B00SZ4QFW0/ref...FEAQ4CK7R6

It does the job fairly well. The guages aren't the best. They relax no matter how tight the system is. That's why I gave a couple psi range. High end pumps and guages will easily pull 30 in/hg and hold on a tight system. This one... meh... I run it for a 30 min to make sure the system is tight then I rerun for an additional hr to make sure its good and boiled for moisture. Then I leave it sit for at least an hour. To ensure it holds somewhere in the 27-28 in/hg range. Anything lower then I know my system isn't tight.

[Rawze]

(06-16-2021 )Kw9006nz Wrote:  

(06-16-2021 )Chamberpains Wrote:  Your vacuum should hold 27ish-30 in/hg (depending how good the Guage is that your using) indefinitely. 30 min is just the least amount of time you want to leave it hold to check for leaks.

Quick ? For you what vac pump do you have? my pneumatic vac can only pull 20-26 depending on weather!

Whenever I do mine, I just let the pump run for an hour or so each time (or at least 30 mins). Gauge does show it gets damn near to 30~ish eventually.

[DVT873]

(06-16-2021 )Waterloo Wrote:  What Snail said, the last AC o-ring kit I bought at International was around $7, and it had enough o-rings to make several repairs in the kit. They are color coded for dummies. I would imagine Volvo has the same kits.

Do you happen to have the part number for that kit? Thanks

[Waterloo]

(06-16-2021 )DVT873 Wrote:  

(06-16-2021 )Waterloo Wrote:  What Snail said, the last AC o-ring kit I bought at International was around $7, and it had enough o-rings to make several repairs in the kit. They are color coded for dummies. I would imagine Volvo has the same kits.

Do you happen to have the part number for that kit? Thanks

No, but it is a regular stock item at the International dealers, just ask for the AC o-ring repair kit. It is nothing more than a small plastic bag of assorted AC o-rings in various colors. If they do AC work, they should know exactly what you are in need of.

[tree98]

(06-15-2021 )Kw9006nz Wrote:  FWIW pulling a vacuum on the system makes the moisture in the receiver dryer evaporate and evacuates all the 0², which 0² makes the freon less efficient in heat extraction and dissipation

So your saying if you pull a vacuum on a system that's been open for a while and evaporate the water you don't have to replace the dryer?

[Rawze]

(06-16-2021 )tree98 Wrote:  

(06-15-2021 )Kw9006nz Wrote:  FWIW pulling a vacuum on the system makes the moisture in the receiver dryer evaporate and evacuates all the 0², which 0² makes the freon less efficient in heat extraction and dissipation

So your saying if you pull a vacuum on a system that's been open for a while and evaporate the water you don't have to replace the dryer?

Moisture issues aside ... if the dryer is more than a couple years old, it is not a bad idea to change it if you have had it apart.. this is because there is also a spring accumulator in it as well that can get weak over time.

[Wildcard]

The receiver/dryer is full of desiccant beads. The absorb moisture and filter out particles any major repair or extended length of time open to atmosphere warrant a replacement.

Best method of leak testing a system is 200psig of nitrogen, soap bubble test and stand test for pressure drop. Nitrogen is a noble and dry gas with little to no change in psi by temp.

Pulling a vacuum in a refrigeration system 26,27 30" is irrelevant. Microns are what's needed to be measured. A tight/dry system will pull to 400 microns and hold for 30 min. Moisture doesn't boil until certain conditions are met in a vacuum in relation to temperature...these are measure in microns. Moisture in a refrigeration system causes copper plating and acid to build in the oil.

[tree98]

And how do you "measure microns" ?