Recharging Avanti R-12 A/C questions

[53k]

It has been a very long time since I have recharged an air conditioner and my memory is non-existent. I need to add R-12 to the '64 Avanti I bought in May. I have the R-12 hoses and gauges and a tank of R-12 I bought back when they were discontinuing it, but I don't remember proper pressures and I don't even remember which is the low pressure side. I did notice that there is a sight glass on the line coming out of the evaporator at the upper passenger firewall. Would that be what I watch while filling? This is an original setup with the York compressor.
Guidance? Thanks.

[bige]

I would replace the receiver/drier before you charge that system with that expensive R12. They have a way of clogging after laying dormant for awhile and are not expensive to replace.

You should evacuate the system after replacing the drier and charge so the low side reads no more than 40 PSI and high side no more than 200 with engine at 1000 rpm and ideally a box fan in front of the radiator simulating air flow at speed.

The low side pressure is important while charging and you should regulate freon flow so it stays between 15-30 while charging.

If there's a valve on the line with the sight glass that's definitely a low pressure point. If you don't evacuate the system or change the drier chances are you will not get a bubble free sight glass no matter how much freon you put in.

[53k]

I would replace the receiver/drier before you charge that system with that expensive R12. They have a way of clogging after laying dormant for awhile and are not expensive to replace.

You should evacuate the system after replacing the drier and charge so the low side reads no more than 40 PSI and high side no more than 200 with engine at 1000 rpm and ideally a box fan in front of the radiator simulating air flow at speed.

The low side pressure is important while charging and you should regulate freon flow so it stays between 15-30 while charging.

If there's a valve on the line with the sight glass that's definitely a low pressure point. If you don't evacuate the system or change the drier chances are you will not get a bubble free sight glass no matter how much freon you put in.

Thanks for filling in the gaps. Yes, I know I should completely clear the system and replace the drier, but I need cooling for our chapter trip tomorrow morning (and I'm a CASO after all). Fortunately my son came over a while ago and he's going to charge it for me (for now). He has done several R-12 to R-134 conversions and he has a couple R-12 vehicles too. He declared it to be low on freon, but far from out. It was cooling, just not as well as it should. So, after tomorrow, as soon as the weather cools a bit, I'll get it done right.

[53k]

My son came back and I broke out my 30-pound can of R-12 (still in the cardboard box as it was when I bought it at Sam's). Lack of a Shreader(sp?) valve fooled us for a minute then I remembered that on my Wagonaire factory air you had to hook up the freon hose and open the valve under the bigger cap. The car took very little and was cooling fine- no bubbles in the sight glass. I guess when it wasn't working well before, the 100 degree temperature must have had something to do with it. Now the compressor belt squeals at the low idle so I guess I'll have to set up a little.

[bige]

Sounds like the belt needs to be tightened. A/C belts need to be VERY tight. If you can see it 'bouncing' while running the compressor it's too loose. If it squeals at idle it will probably make noise on acceleration.

ErnieR

[53k]

Sounds like the belt needs to be tightened. A/C belts need to be VERY tight. If you can see it 'bouncing' while running the compressor it's too loose. If it squeals at idle it will probably make noise on acceleration.

ErnieR

The belt seemed tight, but I think you are right. Today, driving about 140 miles in 90 degree weather the belt squawked every time the compressor kicked on. I need to put on a shorter power steering belt so I will just replace the a/c belt at the same time.