Vacuuming and recharging w/o a manifold gauge set

[WestPoint]

Morning y'all. I've been browsing HVAC forums and many pros vacuum down systems without a manifold gauges. Why you may ask? The reason is to minimize all potential leak points. Leaks can occur at every seal, every connection and a manifold has many connection points.

I'm wondering if I can vacuum and fill safely without going by high/low gauges (eliminate the manifold entirely basically. I have a micron gauge and am filling by weight anyway.

[Tim]

Buy a quality set of gauges and this won't be a problem.

[WestPoint]

Tim, thank you. I bought quality tools to do the job once but I tend to err on the OCD and anal-retentive side of things. Maybe that's why my sleep has been s#it lately

I bought all new for my AC overhaul:

-JB Industries Platinum DV-85N 3cfm two stage vacuum pump
-Yellow Jacket R134a specific 3-way manifold gauge set
-Appion MegaFlow vacuum rated hose with VCRT
-Appion AV760 Micron gauge

I figured buy once, cry once applies for MVAC/HVAC as I have mini-splits at home I could use these tools on.

[JohnHere]

Using a micron gauge is a great way to monitor the precise vacuum while evacuating a system. I use one all the time. But I wouldn't want to forego a good manifold gauge set while servicing a system to monitor both low-side and high-side system pressures while charging and afterward. It will tell you a lot about whether the system is working properly. In my opinion, it's an important diagnostic tool that shouldn't be eliminated.

[WestPoint]

Appreciate the insight John, will go ahead and do it the conventional way with a manifold gauge set!

[WestPoint]

I went ahead and vacuumed down the system last night and recharged the system. It's working great and I am getting 40 degree vent temps and pressures on manifold appeared normal during the recharge.

Now I screwed up when I went to fill with the second can of straight R134a. The first can I purged the primary line right where it meets the manifold and got my hand blasted with refrigerant! Fortunately I had thick gloves on. Now when it came time to connect the second can, I forgot to purge the line again.

Essentially I sent a line of air into a system I prepped long and hard for. Everything is working great (for now) but how detrimental (generally speaking) is a line of air going into the system? I'm hoping to keep the car for a few years so if the AC system can stay solid for 45K miles, I'd be more than happy. This was a great learning experience for an amateur like me so big lessons learned for all future work!

EDIT: I just realized I got no air in!!!!!! Since I was using R134a cans with the self-sealing cans (not sealer inside formula), the can tap does not allow air in as I simply screwed the first one off and then next one on. How did I realize this?! I just went to unscrew the main charging hose from the manifold (other end of hose connected to self-seal can tap) and I got a nice blast of refrigerant to my hand again.