R12 -> R134a 1989 Porsche Kit Questions

[HC3]

I think we've established that.

[HC3]

How would you approach a tech. that is touted as a master auto. tech. but doesn't have a micron gauge? So far I haven't been able to locate a shop that uses an electronic vacuum gauge near where I live (Silicon Valley CA).
I've talked to the guy and he seems reasonable and willing to tackle the evacuation and charge instructions I got with my Porsche retrofit kit (hoses, evaporator, condensers, compressor, basically all new).
I'm thinking he might buy and use a micron gauge if I ask - he already agreed to change the oil on his vacuum pump and wasn't pissed that I asked re. that.
Maybe I'm worrying about too much and bringing this up will just confuse things, the analog gauges are good enough.
Thanks.

[Cusser]

How would you approach a tech. that is touted as a master auto. tech. but doesn't have a micron gauge? So far I haven't been able to locate a shop that uses an electronic vacuum gauge near where I live (Silicon Valley CA).
I've talked to the guy and he seems reasonable and willing to tackle the evacuation and charge instructions I got with my Porsche retrofit kit (hoses, evaporator, condensers, compressor, basically all new).
I'm thinking he might buy and use a micron gauge if I ask - he already agreed to change the oil on his vacuum pump and wasn't pissed that I asked re. that.
Maybe I'm worrying about too much and bringing this up will just confuse things, the analog gauges are good enough.
Thanks.

No one needs a micron gauge for AC work, why you can't find a shop with one. The idea is that at ambient temperatures that moisture (and any residual flush solvent) will boil out of the system. With a traditional vacuum pump and gauge set, one can determine if decent vacuum is obtained, and let that pump 30-45 minutes. Whether a micron gauge or regular service valve gauge is used, VERY LITTLE air will remain in the system.

As Bill Shakespeare would've said: "Methinks you worry too much !!!"

[Tim]

By the time this thing gets repaired, its going to be winter.

[HC3]

No need to get mean! I'm planning on putting the compressor in today using DEC PAG 46. That's the last item.
Above we see bohica2xo recommend using a micron gauge and now it is recommended as not needed.
Maybe you two can hash it out while we watch/listen.

[Tim]

Sarcasm!

Micron gauge is great if you have one. But by no means is it needed!

[HC3]

OK - all is assembled. Multiple flushings of the new compressor and then filled with 5.75 fl. oz. of DEC PAG 45.
I spun the compressor in case we forget when doing the evac. and fill.
The shop loaned me a venturi pump and I bought a HF gauge set.
I'll try my hand at pulling a vacuum and see if I have any "obvious" leaks.
I can get an appointment during the first week in Aug. I'm sure you'all will be waiting for the results.
I don't want to wait until winter - I want the ambient as hot as possible.

[Dougflas]

Those venture pumps are a POS. If you're waiting a week or so, pull the best vacuum you can and place the system under positive pressure.

[HC3]

I can imagine the venturi pumps can't pull much of a vacuum.
Should I pressurize with compressed shop air? Should I get some nitrogen?
The system is "empty" at this point - only ambient air and oil in the compressor.
Thanks.

[HC3]

I can get a bottle of compressed Nitrogen pretty easy around here - not sure of the needed size but they are in the range of $35.
I assume when the shop hooks up to my system to evacuate the left over Nitrogen will not cause any issues.
I need to read up on purging with Nitrogen.