Automotive Air Conditioning Information Forum

i got my gagues and the low side holds a vac for a couple days but after the forth day you can notice a slight bleed down. From what I gather you only hold a vac for an hour before charging so is this really something that needs to be addressed?
lets say I had this leak on the cars end after a few days i notice a hairline bleed down am i really going to be able to find that leak?
thoughts please

Not sure why you would want to hold vacuum for 4 days. You are the only one doing that.
With good equipment most experts advise newbies to vacuum for 1 hr and then charge.
It is more important to get the deepest vac possible.

Remember, a system can leak under vacuum and not under pressure and vice versa.
If you are seriously concerned about system leaks, after you vacuum for an hr, then let some VAPOR in both hi and low sides until you hit 20 psi, then use a sniffer. Sniffers can detect down to 1/4 oz loss per year

Remember, the red blue and yellow hoses are a tiny bit porous to vacuum, which is prolly what you are seeing. The black hoses (more $$) are impervious to vac leaks

hi
In a perfect world every one would vacuum system for 1 hour and vacuum hold test for 30mins with a micron gauge .
Yes u need to check gauges as these can leak by not completely turning ""off"" eg valve seating . Another issue canbe hose sealing etc at connections .