Anybody know how many ounces of r-12 the 77' is supposed to hold?

Thanks,

aka

no but you have a sight glass on the dryer if your charge is low you will see bubbles in the sight glass just charge until bubbles are gone, a empty system usly holds less than 2 pounds r12 can be purchased in 1 pound cans...................at your local auto retailer with certifaction..

thanks for the tip, I am converting to 134a so wanted to know how many ounces so I can do the ratio to 134a ounces. If I understand correctly w/ 134a you can still have bubbles and have the correct charge.

Thanks,

aka

There should be a label on your ac system some were that will tell you how many ounces, be shure to clean all oil out of the system and change your dryer that will screw on and off with 2 nuts, you can drain the oil on the condiser that is the ac radiator in front of your regular one,there is a drain plug on the bottom.
you allways want to charge until you have no bubbles,when your system is empty you need to pull a 30lb. vacum let it stand for a hour this will confirm you have no leaks if the vacum holds,then hook a can of freon up open the valve the system will charge enought then to allow the pressure switch to open witch will allow the compressor to start,you want the fan and ac on max setting,your compressor will click on and off fairly fast becouse your low on freon as the charge builds it will start to run steady this means your getting close,let the system heat well and watch the sight glass charge only until the bubbles just go away .
by now you should be felling some cold air.
Personaly I woulden't use 134a in a old sysyem just isen't that great you better of to have it repaired by a proffisional and charged with R12 this way your garanted a cool sumer and trouble free operation,
Remember don't let the auto store guy tell you to just drop in the 134a you will have problems trying to do it for $40 dollars doesent allways pay off will cost you more in the long run.............

Universal Certified AC tech 75 stringray no AC diden't work so I took it out but I only drive on the weekend with the tops off San Diego Ca.

Good Luck happy Vetting


|UPDATED|6/20/2003 11:32:10 PM|/UPDATED|

Did the R134a thing today. Some air is better than no air, but my mechanic friend wants to try this stuff called Freeze 12 that is an EPA approved R-12 replacement. We'll be trying that either Sunday or Monday (yes, that's right, Sunday believe it or not!) I'll post back and let you know how it goes.

Freeze 12 has it's own fittings and such so you can't use R-12 or R-134a fittings. The A/C in my '77 was in surprisingly good shape. The only snag we hit was a busted valve core that was stuck closed and came apart with half of it stuck in the fitting after removal. Once we got that taken care of we charged with R-134a and the pressure never got over 200 which he said was too low.

Something else he said that was interesting was this: R-12 was meant to be a high flow, low pressure freon, R-134a was meant to be a low flow, high pressure freon, and that's where the problems with proper cooling have they're origin. This guy has never steered me wrong, and he ALWAYS does his homework, so I trust him pretty well. We also do all the work together, so I get to learn loads of stuff. It's a Good Thing(tm) to have a mechanic that owns a part store as a good friend...

Freeze 12 is made in mexico and is not controlled by the montrol protrocal and will do great harm to your system,don"t let the close sounding name of R-12&Freeze12 fool you. someone who would want to install that is trying to save you money the wrong way to put it nicely.........
remember its going to be a long hot summer and you don"t want to spend more money latter........

|UPDATED|6/21/2003 2:47:09 PM|/UPDATED|

I got my manual in today. It says 3 lbs. of R-12.

As to the Freeze 12. Thanks for the tip.

If your friend or menechic is certified and you don't have a 30lb bottle of freon on hand, you can go to someone like napa auto or a other major name and purchase R-12 for about $35 a pound. comes in small cans the same type you used to ba able to buy over the counter.

Thanks for the info, I already discovered it was 3lbs. I ended up having to replace everythign from the evaporator to the condensor. I charged the system w/ 134a last night and today w/ 83* temp w/ 50% humidity I was getting 55* vent temps while driving around... not to far off the spec sheet of 48-52 at 2000rpm w/ hood open measured at right hand side. I did a lot of research on the alternative freons and the biggest thing that bothered me and steered me away was the fact they are blends and have different size molecules that leak out at different rates, so the only way to restore the correct composition would be to evacuate the whole system and start over. I'll let you know how things turn out after the trip to BG and Nashville next week!

aka

I went with the Freeze 12. I was wrong about the fittings, it uses standard R-12 fittings. I weighed everything I was told by many people and I figured the benefits would be worth the risks. I've got COLD air now. We vacummed out all the R-134a (it didn't like my condenser, which is in great shape) and refilled with the Freeze 12. I'm happy with the cooling performance, and once I get my manual heater valve installed and do some duct replacement it will get better. Drove all day today in 95+ temps and it stayed cool in the car. If it does trash all my stuff, then it will just move up the timetable on all the replacement I was planning to do anyway. We vaccum tested before we started with the R-134a and she held 30 lbs vaccum for 2 1/2 hours. Not bad for a Vette that sat in a barn for two years.

I'll keep you all posted on how things progress. clar2001, I asked my guy about your concerns, he said that when Freeze 12 first came out, he wasn't too big on it either. His view was that for older systems that wouldn't take R-134a, Freeze 12 was a cost effective alternative. In the years that he's used it he has not had any ill effects, or he simply would not use it. He's a good friend and he said he'd personally repair any damage that may result from the Freeze 12. As I said, the benefits outweighed the risk in this case. Once again, thanks for the information. It always pays to have an opposing view.