26, 27, 28 psi for r134a poa valve?

[bautino95]

Hi. I'm changing my ac system to r134. I'm finding varying info on what to set the POA valve pressure to. I've read everything from 26,27,and 28 psi. Is the 28 psi closer to icing up the evaperator or the 26psi closer? Let me know what you guys think.
Thanks

[howzzzit]

Search the forum. Several say 27.5. 27.8 is 32 degrees. Go 28.

[bautino95]

So is it a lower psi set on the POA valve make the evaperator colder or a higher psi setting? I only want to do this once since I need to have the system open to make the adjustment. I've searched the forum and like I mentioned above there is varying number to set the POA valve to. Mainly 26,27, 27.5 and 28 psi. If anyone has adjusted theirs, what psi did you use and how good is it cooling?
Thanks

[jumpsoffrock]

Please don't take my comments the wrong way or me being "snarky".

But remember this is a hobby playing with old cars. There is essentially no such thing as "I'm only gonna touch this once and it'll be perfect forever"
If any part of the restoration of these old trucks was that cut-n-dry, they'd be a whole lot easier to restore.

I have not finished my A/C conversion, but I also remember researching POA adjustment. Just the same as people who modify stock brakes with aftermarket setups, or people who change carbs, or people who switch to FI engine with auto overdrive, or people who update their interior with tons of new parts like seats and dash's and gauges and soundsystems.......every one of those people/situations typically calls for multiple adjustments that are unique to that person/truck/situation.





Long story short you're gonna have to play with the POA(and probably me too). I highly doubt there is a perfect final solution that you can set it to for optimal performance.

[leddzepp]

If you only want to do it once, use r12 like the system is designed for and enjoy ice cold air and don’t monkey with anything at all.

[Richard]

The TXV is what sets the evaporator coil temperature for cooling. The POA is a bypass that keeps the evaporator from freezing up to keep it above freezing temps. R12 is a thing of the past and the cost is way to high. A retrofit can be done properly with the knowledge.

[leddzepp]

R12 is readily available on OfferUp, Craigslist, etc. It’s not that expensive and you do it once. It’s not like a gas tank that constantly needs replenishing. I played the r 134 conversion game and wasted more time and money trying to make it work. I went back to r12 and have ice cold air in 100 plus degree weather sitting in traffic with no movement. My factory ac has worked flawlessly for many years now. Do whatever you want, good luck.

[Sheepdip]

Originally Posted by bautino95

Hi. I'm changing my ac system to r134. I'm finding varying info on what to set the POA valve pressure to. I've read everything from 26,27,and 28 psi. Is the 28 psi closer to icing up the evaperator or the 26psi closer? Let me know what you guys think.
Thanks

You are on the right track by keeping the POA valve. I converted to 134a and I tried one of those junk pressure switch replacements for mine. Ended up throwing it in the sh*t can and bought a used pre-tested and calibrated POA valve of the re-buildable variety off ebay. System has worked flawlessly. I don't have your answer but I would go the middle number 27 and forget about it.

[howzzzit]

LeddZepp is spot on with the R12. Best refrigerant ever produced. I'm still running it in my C10, but I do have some in stock. Just so you know R134 is being phased out of commercial equipment. Don't know what that means for the average guy that will need it for their auto. R22 has been phased out and R410 is right behind it. You have one of those in your home air conditioner. Back when I first started in commercial refrigeration there were three refrigerants mostly used. R12, R502, and R22. The world's leading countries decided to fix the ozone and phased out R12 and R502 to start. Other countries had no restrictions. The point? None. The EPA and air resource boards are here to help you. Trust them they're from the government. Sorry for getting off topic.

[67 twins]

Originally Posted by howzzzit

LeddZepp is spot on with the R12. Best refrigerant ever produced. I'm still running it in my C10, but I do have some in stock. Just so you know R134 is being phased out of commercial equipment. Don't know what that means for the average guy that will need it for their auto. R22 has been phased out and R410 is right behind it. You have one of those in your home air conditioner. Back when I first started in commercial refrigeration there were three refrigerants mostly used. R12, R502, and R22. The world's leading countries decided to fix the ozone and phased out R12 and R502 to start. Other countries had no restrictions. The point? None. The EPA and air resource boards are here to help you. Trust them they're from the government. Sorry for getting off topic.

The point? Money. You can be sure that a few people made a whole lot of money from this. The answer is always money.