AC retrofit to R134A

[70 gmc c2500]

My son recently picked up a 70 GMC C2500 with factory AC that wasn't functioning when he bought it. Someone in the past replaced the compressor with an aluminum 10 cylinder compressor that replaces the cast iron, 6 cylinder axial A6 style and installed R134A fittings but apparently nothing else. From my understanding I need to replace the condenser, receiver/drier, expansion valve and do a POA conversion? With that being said I took a look at oldairproducts.com and found those components...

50-2551A POA update kit
25-0057 Expansion valve
51-7211 Superkool condenser kit

Would these be the correct parts needed?

I also understand that the evaporator and the compressor will need to be properly flushed and then once all the new parts are installed the system will need to be vacuumed down and then proper oil and amount installed and the system charged back up with the proper amount of R134A. Am I missing anything or have I got it under control?

[Richard]

I would avoid the POA update. You will probably be disappointed. It is just a patch to convert the system to a cycling clutch system. If going to a cycling clutch you should just go all the way and also go to a fixed orifice and eliminate the expansion valve. The oem's did this long ago to decrease cost. Either convert original system correctly to operate with the new refrigerant or get an aftermarket system. The aftermarket systems have more drawbacks than I want. Though I am more concerned about capacity, longevity and do not give a hoot about a smooth firewall and a show type engine compartment.

[Sheepdip]

I will echo Richard...If your POA is good keep it, have it cleaned, tested and recalibrated.
It will make life much easier.

[kaycee]

I ditched my poa valve and got a drier,evaporator (88 C-10) from Rock auto an e-bay condenser and a nice used comp Sanborn 508 from the forum and a hose kit from old air. Been blowing cold for 2 + years .it uses all the stock covers and wiring .

[68 C10 Driver]

Be aware that the current system will require a flush to get rid of as much of the old compressor oil as possible. R134 with Polyalkylene Glycol (PAG) oil.

[mrein3]

Its been years but I found my post. I converted my non-AC cab to factory AC with parts mostly from a factory AC truck. The compressor was off a car of this vintage. ALWAYS buy a new receiver/dryer. Replace all the o-rings.

If you're starting with an already factory equipped AC truck, you're miles ahead of where I started.

Anyway, here is what I said right after I did the conversion - which still works by the way.
https://67-72chevytrucks.com/vboard/...d.php?t=478564

[ochremo]

Another option. I also have factory air that needed rebuilt and switched over. I called these guys on a Sunday two years ago to leave a message asking a question. He was on the road and picked up the phone ended up having a long discussion. Great people explained everything well had the parts in three days.

https://autoacsolutions.com/products...-and-tube-kit/

[70 gmc c2500]

So I got ahold of oldairproducts in Texas and ended up ordering everything from them, new Sanden 508 compressor, updated POA valve, expansion valve, hose kit, new condenser kit and a 180°fitting to go to the POA valve.