A/C questions

[bobcooter]

 When I bought my 79 C20 the A/C compressor clutch was wiped out. I replaced it with a remanned one and converted it over to R-134a. It blew cold but it took it a good while to get comfortable inside the cab in the summer. About 15 minutes before it felt alright and that was with leaving the windows down all day before getting in. I did not flush the old R-12 residue out of the system which I know was a mistake. Now, the remanned compressor is knocking so I am going to replace it with a new one, change the dryer, replace the orifice tube and put a new pressure switch and flush the system before putting it back together. I own a vacum pump and a set of gauges.
My questions are:
1. How much R-134a does it take?
2. How much and what type of oil does it take? (I put the PAG oil in the compressor when I replaced it.)
3. Is it necessary to replace the condensor? It looks to be in fine shape form the outside.
4.Am I forgetting anything else?
 I got my info off the web (not here) before doing this the first time last summer, but I have learned that simply because you read it on the internet doesn't always mean it's true or correct. I trust you guys.

[VileZambonie]

Is it an A6 compressor? Yes, fill the compressor first. Try to get 10 total ounces in the system of ester oil (60z if it's an R4).

Flush the sytem out with nitrogen if possible.

Replace the accumulator and orifice tube.

Vacuum the system for at least 30 minutes.

Recharge it with R134A at 5lbs if it's an A6 or 3.5 lbs if it's an R4

[bobcooter]

Thanks Vile. It's the old long style compressor. I think those are A6?
"Recharge it with R134A at 5lbs if it's an A6 or 3.5 lbs if it's an R4" I'm not quite sure I understand.
What kind of low side pressure should I see when it is fully charged with 134A? The temperature down here is running in the low to mid eighties every day now.
Are those flush kits they sell necessary? I don't have access to nitrogen but I have an air compressor.
Thanks in advance for your answers.
 

[VileZambonie]

16 oz = 1 lb

So if you are using 12 oz cans just do the math. If you are using a scale then it should be self explanitory. Yes you have an A6 compressor. The low and high side pressure will vary based on temperature and humidity. Charge it accordingly at 80% and report your operating pressures along with the temperature and humidity. If you use compressed air make sure it's clean air no rust and moisture saturated air. Make sure the accumulator is off when you do it too. Vacuum the system for at least 30 min. Measure how much oil you pulled out of the system after you vacuum it and put that much back in. Then do your initial charge.

[bobcooter]

Thanks for the help!