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Re: R12 -> R134a 1989 Porsche Kit Questions
Posted: Thu Jul 20, 2017 6:35 pm
by HC3
In the forum archives there is a thread on this for a car like mine where the two condensers were added/etc. The guy is in exactly the same place I'm at this point.
Line Purge & pressure test procedue with Nitrogen
mthomas58 on Thu April 03, 2008 2:23 PM User is offline
Re: R12 -> R134a 1989 Porsche Kit Questions
Posted: Thu Jul 20, 2017 6:55 pm
by HC3
Purging with Nitrogen doesn't seem to complicated.
Open the low side port to the outside, inject Nitrogen on the high side port and flush for awhile.
Close the low side port and add Nitrogen until the pressure is ? 20 psig and close everything up.
Then I check for the gauges reading lower over the next few days. Something like that?
Thanks.
Re: R12 -> R134a 1989 Porsche Kit Questions
Posted: Thu Jul 20, 2017 8:14 pm
by Cusser
HC3 wrote: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.
Well, typically vacuum is applied soon after the drier or accumulator gets bolted on and system closed, because air contains moisture, the system is really not "empty". Autozone near me has free loaner electric vacuum pumps. Try that.
Re: R12 -> R134a 1989 Porsche Kit Questions
Posted: Fri Jul 21, 2017 5:49 am
by HC3
Good point there is moisture from the air it there at this point.
I'll check with my local Autozone and see if they have loaner pumps.
Re: R12 -> R134a 1989 Porsche Kit Questions
Posted: Fri Jul 21, 2017 12:48 pm
by HC3
Got a set of gauges from HF.
Borrowed vacuum pump from Autozone.
It is now pumping - showing 31 " Hg.
I guess leave it run for 2 hours and then shut it off and see how things hold overnight or during the rest of the day.
I shut the pump off just after starting it for a minute or so and the vacuum gauge didn't move. So I think I have no big leaks.
Here are a few pictures.
Re: R12 -> R134a 1989 Porsche Kit Questions
Posted: Fri Jul 21, 2017 1:48 pm
by Tim
If it held a vacuum for 5 minutes after shutting off. Charge it. No need to let it sit over night!
Re: R12 -> R134a 1989 Porsche Kit Questions
Posted: Fri Jul 21, 2017 2:01 pm
by Cusser
HC3 wrote:It is now pumping - showing 31 " Hg.
I guess leave it run for 2 hours and then shut it off
2 hours is overkill.
Tim wrote:If it held a vacuum for 5 minutes after shutting off. Charge it. No need to let it sit over night!
Agree.
Re: R12 -> R134a 1989 Porsche Kit Questions
Posted: Fri Jul 21, 2017 3:10 pm
by HC3
I don't have a way to charge it.
Need to take to the shop and they can't get to it until the first week in Aug.
Re: R12 -> R134a 1989 Porsche Kit Questions
Posted: Fri Jul 21, 2017 4:14 pm
by Dougflas
HC3 wrote:I don't have a way to charge it.
Need to take to the shop and they can't get to it until the first week in Aug.
Yes you do have a way to charge it. Two hours of running a vacuum is not overkill. That system was open for a long time. If the pump usage doesn't cost you anything, let it run a long time. Close both hand wheels. Remove hose from vacuum pump. Buy a small can of R134a and a fitting for the can. Connect the free hose to the fitting and can. Puncture the can. Bleed the hose at the manifold. Open the high side hand wheel and the low side hand wheel. Allow R134 to enter the system. Now the system is under positive pressure and can wait until your shop can charge the system. You do not want to leave the system in a vacuum for that amount of time.
Re: R12 -> R134a 1989 Porsche Kit Questions
Posted: Fri Jul 21, 2017 4:41 pm
by HC3
ok - I'll work on that. I'll turn the pump back on and open the manifold wheels. Has been off for a couple of hours and the needle doesn't seem to have moved still showing 31" hg.
Is there good and bad quality R134a in the small cans? No worry of mixing with the shop's R134a?
I guess I want no oil or dye.
I need the fitting that will connect the can to the yellow hose and then allow me to puncture the can, right?
Thanks.