im installing a new compresson into my 72 cutlass and i need to know how many oz or lbs of r12 (freeon*) to put into compressor...please help me before the hot weather comes

 

From the '72 CSM:



- Eric

 

I think you need to take it to someone licensed to get r12. Not sure about your state but here in TX you cant put r12 yourself.

 

Yeah. There's lots of things you "can't" do yourself.

Except you can.

- Eric

 

Couldn't have said it better.
If you have the evacuator, gauges, and knowledge, and the system was functional and holds a healthy vacuum for a while, then go for it. Make sure the little valves in the charging ports are in good shape, and tight before hand (use a tire valve tool to check.)

 

Yeah, if you keep your eyes open, you can get R12 recovery units really cheap now. I got one for $30.
The garages aren't doing R12 anymore and they just want to get rid of that junk.

If you need to buy R12 legally, you can take this test from the EPA: www.epatest.com/609/ (I'll make a fancy link when I'm not on my phone), through Mainstream Engineering, which is certified by the EPA to certify technicians.

- Eric

 

I got some r12 and put it in but ac still isn't working...the lines are frosty...do you guys know what's wrong?

 

There are a raft of possibilities.

Do you have a gauge set? What are the pressures?
What's going on in the sight glass?

- Eric

 

how much did you pay for your R12? that stuff is high enough now that you want to be very sure your system is good before adding the R12. last i knew it was around $100 per lb. i see little cans at flee markets now and then for $20 each.

 

Yes, we must know the high and low side pressures, the fan speed you were using, and ambient (outside) temperature. How much did you put in? Stock A/C system?

 

I think the system holds about 4-5 cans or lbs of R12. As said you can charge till sight glass is clear on receiver drier. If still not working you need gauges to check pressures.

 

i used gauges and the pressures are fine...i dont have a sight glass haha so i guess its a gut feeling....i got the r12 from my uncle, he bought lots of it years ago before it went out...and we put in 4 cans......NEW update i opened up the dash and looked at the doors and flaps and they are working fine but that coil radiator looking thing isnt cold at all when i turn on the AC, so is it possible that there is a blockage and its not allowing the coil to get cool?

 

If there was a blockage, then pressure on the high side would be too high. Belt could start slipping, too. What actual numbers were you getting? We cannot really help unless we know the specifics - pressures hi & lo, temp, RPM, fan speed.
Did you evacuate the system with a vacuum pump? If it had air in it, then evac is a must.
With normal pressures, the evap should be somewhat cool.

 

Do you know where to look for the sight glass? What lines were frosty? Are you sure the compressor clutch is engaging? Yes pressure readings seem like a must now.

 

also, is the clutch engaging on the compressor when you turn it on?

 

Why not?

Has the receiver been replaced?

It should be right in the top of the receiver, visible through a hole in the top of the core support, which probably has a rubber plug in it, as in this picture:



And while I'm at it, here are the performance specs for you to compare with:



- Eric