Charging A/C First timer

[jjzepplin]

I have never had a classic with working A/C. So here goes. I have a complete stock setup from a 72. The compressor and belt system is from a 1992. Compressor is the R4 I believe. I have pulled a vacuum and it's holding. I have replaced the drier. The condenser and evaporator had a bit of freon and oil in them when raped from the junk yard. I am thinking r134 but may go with r12. But what about oil? Any help from A/C guru's?

[Transformula]

Yes, you do have the r4 compressor (Radial, 4 cylinder). PAG oil is great for retrofits of 134a where r12 once was. Be sure to flush all lines, evaporator, POA valve, condenser, etc. Drain the compressor of old oil and add some with the front facing down, through the inlet port and rotate the drive a few times. This lubes the front seal. They even make a retrofit vavle with a compressor cycling switch to replace the POA valve that is usually no good anyway.

[67c10rustbuket]

Was the condensor and evaporator coils from the '92 or a 67-72? Just wondering as I read others say that the 67-72 condensor is too small to efficiently cool on 134 systems. The '92 would have been R12 so just as transformula said if you go with R134 it would need flushed and have PAG oil added. The compressor label should specify how much oil the system needs. I dont recall the weight maybe PAG100? there are several PAG oil weights hopefully someone else can verifty the proper oil weight for you.
R12 cools better but costs a lot more while R134 is readily available and costs less. I converted my '93 from R12 to R134 and it works great. I also changed all the o-rings and seals out with the new green ones that are supposed to be for R134 but have seen plenty of people use the old black o-rings without problem.

[jjzepplin]

Just the compressor is 1992. Rest is stock 72. Do I need to change the poa? It was on a charged system. I assume it still works. Did I screw up my new drier by installing it and pulling a vacuum?

[El Campo]

Did the stock 72 line bolt right up to the compressor?
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[mrein3]

Originally Posted by jjzepplin

Just the compressor is 1992. Rest is stock 72. Do I need to change the poa? It was on a charged system. I assume it still works. Did I screw up my new drier by installing it and pulling a vacuum?

If you're going to use R134a, you do need to adjust your POA. ackits.com used to have a really nice post with pictures on how to do this. However the pictures weren't there the last time I looked. Post #4 in the link below has a link to the ackits.com forum where I learned how to adjust my POA.

You didn't screw up your receiver/dryer as long as you don't leave it open to the atmosphere.

Where you are at this is what I'd do.
Flush the evaporator and condensor with mineral spirits. First remove that new receiver/dryer and plug both holes then flush back and forth with mineral spirits and compressed air. This is messy but necessary. Don't worry about getting all the mineral spirits out as when you pull a vacuum it will all boil out with any remaining moisture.

Replace ALL o-rings with new ones. ALL of them.

Flush the compressor with oil like Transformula said. I bought 1/2 gallon of R134a compatible oil from AC kits which was enough for 3 or 4 flushes of my compressor and the 11 ounces you need for the system when you're ready to close it up. I still have about half of that half gallon for future projects.
Note that the R4 compressor you're choosing to use is the same compressor that scared all the old-school guys I know away from serpentine belt drive systems. Those things like to lock up and with one belt you're stuck.

The stock condenser on this vintage of truck is not the most efficient but because the cab is small it will work. R134a isn't as efficient at cooling as R12 is so modern cars and trucks have condensers with many more tubes giving much more surface area to help with taking the heat back out of the coolant.

I did a detailed post about my AC job in here:
http://67-72chevytrucks.com/vboard/s...d.php?t=478564
Scroll down to post number 8 to see all the part numbers and prices for the stuff I bought.

I hope this helps.

[jjzepplin]

oops