I need some advise on converting from r12 to 134a on my 68 442. Every though the car is a convertible, a/c is a must here in Houston during the summer months.Everyday this week its projected to be over 100 degrees. So far I have changed the compressor because it was bad and put a new dryer on it. I have also replaced the blower relay switch which was also bad.
I believe in order to change to 134a I would need to change the POA valve and and expansion valve. Is there anything else I might need to do? I want to make the change to 134a because as you know r12 is next to impossible to get and if you do find it the asking price is a bit much. I am also thinking about maybe going with vintage air system. Any thoughts or advise is much appreciated.
Thanks in advance
Gary

 

I hear ya about AC being mandatory in a convertible. I bought mine in a small town way south of Houston on the coast and have lived in areas where 100+ summers are the norm.

There was a discussion about R12 a couple moths ago and multiple folks posted about R12 for sale at reasonable prices.

But back to you questions. You don't need a new expansion valve or POA valve.
As far as I know, there is no difference in expansion valves between the two refrigerants.
The POA valve you have should be able to be adjusted for use with R134A. There's a screw in the large opening that can be adjusted to allow lower pressure (and therefore lower temperature) for use with R134A. Do a search on the site as there's a good thread about how to perform the adjustment. Some folks have even reported satisfactory performance wothout adjusting the valve, but the adjustment will provide better cooling.

 

I’d keep it Orig, I’m getting my system charged this week for Dream Cruise.

 

The prevailing wisdom is that a new condenser is in order....and hoses probably wouldn't hurt either.

Cost effective is not really in the equation. R12 is available and it's not as prohibitively expensive as it used to be (check fleabay and craigslist). Sure, the cost of refrigerant is cheaper but the parts and labor required negate the cost savings.

Cheers,

Troy

 

x2

Replacing the hoses isn't just a good idea it's mandatory unless you want to keep adding refrigerant.

R12 is available now but there are also R12 substitutes available. If you want to keep your car original then I guess Vintage Air is out, but it would definitely work better than R134a in an R12 system.

 

Just as a summary, you have several options.

R12 can be viable, check around.

R134a conversions can be done in several ways depending on how thorough you want to be and how much performance you want out of it. Flushing out as much of the old oil as possible out of the entire system is a good idea. You have to use ester oil if any old mineral oil is in there. If the entire system is completely clean then you can use PAG. PAG+mineral=failure. There's no changes to the expansion valve - it just needs to work. You *can* adjust the POA valve, but it's not strictly necessary - there's a sticky thread about that. You *can* replace the condensor with a parallel flow, but it's not strictly necessary. Old Air Products has a direct fit one these days - expensive, but much simpler than what I did.....

Regardless, rebuilding the hoses if they haven't been within the past decade is a very good idea.

The POA "replacement" valves are not an upgrade. It's just a different way of doing things. The problem is they are cycling switch - they disengage the compressor, whereas the POA system keeps the compressor running all the time. The A6 has really heavy internals and wasn't designed to cycle, so it'll wear out the clutch.

 

Thanks everyone. I do see R12 on Ebay at about 30 bucks a can. I am going to pull a vacuum on the system to make sure there are no leaks and possibly stay with the R12.

 

as a HVAC mechanic and someone who has done multiple conversions, stay with the R12 you are not going to get another refrigerant to perform as well as it does you can put in a new system and it will not work as well as the R12 and as you've found the R12 prices have come back down, you will save money sticking with it!

 

Learn from my mistake:
I pulled a vacuum on the system using both high and low pressure ports. Vacuum held for over 24 hours, so I charged the system. I later found bubbles at one of the charging ports. Apparently the schrader valve had a slight leak that I did not detect because I had the gauge connected to it. So what I should have done is checked the vacuum with the gauge connected to one port, then switch to the other and check it again. Or just replace both schrader valves.

 

Good information Kenneth. I will keep that in mind as well. I also found some r12 on ebay and bought some cans because my 72 is going to need to be charged as well. Looks like the going rate is about 30.00 bucks per can for 12oz or 14oz. Before I even think about gassing the unit up, I am going to make darn sure there are no leaks.

 

I am sticking with the r12. thanks for your help.

 

^^^ This guy knows what he is talking about.
R134 = barrier hoses, silicone o-rings, system flush (acetone works), poa tested and adjusted, modern A10 aluminum compressor (called s6 also) on factory brackets, parallel flow condenser. Maybe add a fan on condenser for 100F+ idling for 1 hr without meltdown.

BTW, Vintage Air is not that great. Check out Classic Air of Florida.

 

I did this a couple years ago.....and I've said this a few times so forgive beating the dead horse.....

I'd say if it holds vacuum etc....sure, fill 'er up with R12 and see what happens. If you get away with just adding a can of r12 here and there, awesome.

If not....as was my case.....I just replaced everything. Compressor (Pro6ten), condenser, evaporator, adjust POA valve, hoses blah blah blah. I also converted to 134.

Now, it may not be as cold as r12 but there are a lot of automobiles out there that cool just fine with 134 as well....

Just my .02

Cheers,

Troy

 

I had a open system for years so I decided to replace most all of the system and switch to R134a. It was a royal PIA. Replaced compressor, hoses, expansion valve (set for 134), condenser ( also for 134) etc. It was a very drawn out and unpleasant experience, but is done now and works good. If I had it to do over again I probably would have converted the system as I did, except give the car to the a/c shop and told them to do it all, that way if there were problems (as there was) it would have been all on them. I had ordered all the stuff from vintage air in Florida, then replaced it myself, then took to local shop for evacuation and charging. Had to send back leaking rebuilt compressor which I had to pay shop to remove and replace, and shipping. Then the shop overcharged the system and gave back to me. I left for the Olds Nationals in Springfield Ill. and had smoke coming out of my hood from burning up the clutch! They had overcharged the system! As I said it was a PIA! Anyway if I had a existing system that was complete or mostly OK I would have stayed with R12. Good luck and let us know how it goes!

 

Just throwing this out there...

I had an ‘88 300zx R12 system that I pulled a vacuum and let sit for two days to watch for leaks. None were apparent so charged with gold (R12) and it leaked out in two days! Had a leak in pressure switch that only leaked under pressure. So, vacuum is not 100% reliable indication.

 

Just threw a LB in mine

 

You are correct about the r12 availability. Since this initial thread I have acquired 13 14oz cans from ebay and craiglist with an average of about 20 bucks a can. I have also purchased a link detector off ebay.

 

If you installed a new dryer on an open system it is now ruined, throw it out. The dryer has to remain sealed or it will absorb moisture and become useless. It should be the last thing you install in the system right before you pull a vacuum on it.

 

Appreciate this information but I have already pulled vacuum on it two days ago and so far its holding vacuum. As soon as I get the oil charge in, I am putting a can in the system as well as 1 14oz can of freon and see what happens. I am also waiting on the leak finding just in case there might be a leak, but the vacuum holding is giving me doubts there might be a leak. I am going to let the one can sit a couple days and see if there develops a leak. Not going to fill it up and possibly loose it.

 

You can get your orig accumulator rebuilt like new, I’m doing that.

 

I bought a new one from O reillys for 18 bucks. I did not know that the dryers could be rebuilt however. Where its located cant see it anyways.

 

I just wanted to let everyone know that my a/c now works very well and I have no complaints. I did not change the hoses nor the evaporator or the condensor. So far I am not experiencing any leaks. I bought myself a leak detector and I am constantly checking it for leaks. The only things I did change were the compressor, the dryer and the relay switch which I bought all from O reilly's. I did stick with the r12 freon. Thanks for everyone suggestions and guidance.

Gary

 

Great to hear!

Keep on rockin' in the free world!

Cheers,

Troy