So I am almost done the resto on my 77 shortbed 4wd and it has the york style compressor horizontal mount...and the manual calls for 10 oz of oil and 2 lbs of r-12..........there was a factory oem sticker on the inside of the glove box that said max charge of 2.75 lbs?? So which is it? 2 or 2.75 lbs? Also I will be using a r-12 substitute known as freeze 12 and I'm suppose to use 80% of the oem charge for the freeze 12. As for the oil, I have a new condensor, new expansion valve and all new lines and I flushed out the evaporator, I did not drain the oil in the compressor but I will be checking it and draining it and replacing with new mineral oil or ester oil? As for the oil since freeze 12 is a 80 percent mix of 134a and 20 percent 152b refrigerant, Anyone know if I should use ester oil or stick to mineral oil?

 

anyone got and ideas on the above questions?

 

R12 uses mineral oil; Freeze12 uses Ester oil; exclusive R134a uses PAG oil.

R12 oil and Freeze12 oil are compatible....if you can't get all of the mineral oil out there should be no issue.




You know, the internet can be a maaahvelous tool............

 

Did you replace the dryer? (if no, you need to) You do want to drain and fill the compressor (that oil is part of your total calculation) - I've ready where some of the oil goes in the compressor and some elsewhere (not all of it goes in the compressor).

 

yes it is new as well.....the oil is cycled throughout the system

 

thank you..........Am I not using the internet as a tool??

 

You're welcome....and, yes, you're right - the tool in question is being used.
I stand corrected....

 

I knew what you meant.............thing is I work on cars all day and have a short window in the evenings and early mornings to work on my projects, amongst trying to finish up converting my garage at home to a living space, spare time has been next to none. While I'm a well versed tech, the days of r-12 and r-12 substitutes were being phased out when I started my journey into the tech world. And I have used ester oil plenty, just wasn't sure since freeze 12 is a mixture of 134a and 152b that I was suppose to use ester vs mineral oil.....but it does make sense, since we used ester all the time in 134a conversions.

 

So anyone know if the charge amount is 2.75 lbs as stated on the sticker I found in the glove box or 2 lbs as manual states?

 

Is not the sticker (2.75 lbs) manual (2.0 lbs) for R12 use? I think exclusive R134a uses 1.8lbs. Since you're using the Freeze12 which contains R134a and 152b could you not split the difference?

You know more about this stuff than I since you work with it...but I would err on the low side....

 

well either way it's 80 percent of the original r-12 amount that has to go in........with r-12 you could add refrigerant without measuring in theory and watch the sight glass and when all the bubbles were gone and a/c output was good, you could assume it had a full charge....however with 134 a and substitutes that contain such, that method gets thrown out the window. More charge than specified is not better in an a/c system and will reduce performance which is why I'm trying to figure out what it calls for.......2 in the manual and the sticker says 2.75 max, .75 is a big difference = 12oz...... right now I'm vaccum leak testing the system so not much time left to figure it out.....I can always start with the lower amount and add more if needed.

 

I know more charge doesn't equal a better cooling system on the newer vehicles...

My thought was/is as yours - start with a lower amount and then add as needed since the "new" stuff requires less to function fully.

Good luck!

 

thanks.......well it's Friday, most likely I'll charge it Monday as no way in heck I'm leaving work late today, right now it's in a leak test mode, seems to be hold 30in.hg so another 20 min on leak test and if it doesn't drop, it should in theory hold the charge, gotta add 10oz of ester to the system then should be ready for a charge. Right now I'm setting up the scale that is an old electronic mac tools scale for measuring refrigerant on 30 lb cylinders, so we'll see soon if that works!!! crossing my fingers!!!, man if this was 134a I'd of been done by now..lol machine does all process in 1........with this r-12 I have a separate tool to set up for each process

 

Update, so it holds 2 lbs, freeze 12 instructions were to use 10 percent less than the oem charge and anymore than 2 lbs , pressure spiked and cooling went south... anyway, with the proper charge of freeze 12 on a hot humid day best cooling I could get was 54 degrees= not acceptable!!!! So out went the freeze 12 and I hunted local craigs list for some cans of r12.......and I found 3 cans locally, Charged it up with r12 yesterday and bam!!!!! 39 degrees output!!! fogs the windows now with all the humidity here...lol So there you have it, freeze 12 vs r12 = no comparison, or at least using a york style compressor the results have been less than desirable and this isn't the first time I've tried doing such.

 

Thanks for the update...glad you figured it out.

Too bad you spent all that time and dollars on an upgrade when all you (maybe) needed was new seals/o-rings.

I'll file this one away as a win for R12. Glad you found a few cans...I think the "powers that be" are phasing every thing out for the "new and improved" 152b.