Quote:
Originally Posted by ziddey
I've got a 1990 vw fox that originally had r12. I didn't get a chance to see the pressure remaining in the system, but it was low enough that the compressor no longer cycled on. I had the system evacuated and it held vacuum. Nothing was ever touched with the ac system. I didn't change any o-rings or the dryer, but just went straight to r134a. I made the mistake of only finger tightening the r134a retrofit valve and by next day, the system was empty. R134a was never that cold, especially at idle. Weak compressor..
I haven't paid attention to the retrofit valve. Is it just metal, or is there a plastic washer in there? Or is that part of the quick connect? Either way, I can't get the quick connect on there anymore, so I'm hoping it's not part of the retrofit valve (since it said that the valve has some sort of adhesive that would make removal "impossible" without breaking the original valve with it).
I'm going to get the system evacuated again.
So at this point, the system has seen r12 and whatever the original oil was as well as r134a and whatever oil that came with (pag I'm imagining). I'm still not going to change the o-rings / dryer (I know I know..). I just got a 12pack of hc12a, which I understand is the same as duracool. I'm a lazy bum, but I recall reading before that duracool/hc12a is an aziotrope? Is this right? It'd definitely suck to have it slow leak and then not be the right proportion anymore.
Does the hc12a bottle come with any oil? If not, what kind of oil should I be using, and how much of it? Is PAG ok? Or should I switch to ester after the evacuation?
Last time I paid a guy $40 to pull vacuum. But I figure maybe it's time to just purchase a vacuum pump. What's a good cheap one to get? I see a lot that are $100. any less than that? I've got harbor freights nearby and hear I should pick one up there.
I'm a big support of duracool based on everything I've read so far. Hopefully that won't change after I try it out. I'm really hoping that the bigger molecules would mean that the system will be problemfree for a long time, even with aged o-rings.
Let's hear some more about duracool
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R-12 uses mineral oil and R-134a uses polyol ester. I'm not sure what duracool uses but ES-22a can use all the common HVAC oils. I have never heard of PAG. Is that alkylbenzene?
As for a vacuum pump, take the compressor (and its capacitors and relay) out of a discarded freezer (not a fridge, it must be a freezer as only those are designed to pull to a low pressure). Attach a 1/4" flare to the suction line (leave the discharge line open) and there's your vacuum pump. You'll also need a gauge set if you don't already have one, and a good one will be about $40 from a HVAC supply store. Also get a splitter and two valves if your gauge has only one service connection. (That essentially upgrades the gauge set to one with 2 service connections, for a lot less than buying one with that feature.)
It is recommended to do a "triple evac" by pulling a vacuum for about 3 hours, using a dry, clean gas such as nitrogen or CO2 to break the vacuum (pressurize up to about 150PSI for leak test), pull a vacuum for another 3 hours, break again, pull again, and then proceed to charge up the system. Check subcooling for TXV systems and superheat for capillary tube systems.
It is actually not as hard as it sounds. Ask me for more details. You may also want to check the following link. They mostly deal with air conditioning high end computers but you can learn a lot from them.
Vapor Phase Change Cooling - XtremeSystems Forums