Full Size Jeep Network

I have a R134a converted ac system with a york compressor and Im going to be evacuating the system to replace the service valves. I came across a couple cans of R12 refrigerant and would like to charge with that instead of r134 when I recharge the system. I currently have ester oil in the compressor. What all do I need to do to go back to R12 besides just fully evacuating the system?

My understanding is that ester oil is fine with both. Fully evacuating the system should be fine. Would let it run for a while to pull everything out and make sure it is holding vacuum.

Only downside may be if you have to evacuate the system again. Most places won't evac a system with r12 these days. So I would make sure your system has 0 leaks.

Might be a good idea to replace the drier while you are at it, but that means opening up the system to air. Which means you should probably evac it again after that.

And if you don't have a binary switch installed inline, I would do that as well to protect your compressor.

1979bettywhite wrote:My understanding is that ester oil is fine with both. Fully evacuating the system should be fine. Would let it run for a while to pull everything out and make sure it is holding vacuum.

Only downside may be if you have to evacuate the system again. Most places won't evac a system with r12 these days. So I would make sure your system has 0 leaks.

Might be a good idea to replace the drier while you are at it, but that means opening up the system to air. Which means you should probably evac it again after that.

And if you don't have a binary switch installed inline, I would do that as well to protect your compressor.

I have a fully functioning system now with no leaks. The service valves just are kinda siezed up and don't like to move very well. I contacted the manufacturer of the ester oil I used and they said it is not r12 compatible due to some additive they put in it. The drier is only a year old would I still need to replace it?

My understanding is that it's a good idea to replace the drier any time the system is opened for service.

On the oil, ester is the preferred "transition" oil when converting R12 to R134a. Now in going back from 134a to R12, I would guess that you would be better served to remove all the ester and replace with mineral oil. This is where it may be a little more difficult. You can use some sort of hand pump to extract all the oil, or remove the compressor and drain it all out. Those are probably your two options for replacing the oil.

Since there was a different oil running through the system and you are going to a new oil, I would probably go ahead and replace the drier to be on the safe side.

Did you change out the expansion valve when you did the R134 upgrade? If so, the R12 won't be as effective.

If you need to charge the AC, why not just toss in a can of R134? That would be a lot cheaper and easier than trying to use the old R12. Sell the R12 to someone who still has an R12 system.

Idunno, changing the service valves on a fully functioning system seems like a waste of time and asking for trouble. I'd hold on to them until the system did need service.

You'd definitely need a new drier. Unless you're doing a solvent flush you'd never get the oil out of it. Even then you'd want a new one since it's a trap and you'd have trouble getting the solvent out.

If it's working ok with 134 I wouldn't change back. You have the R12 now but what about next time it needs service after you switch back? Might not be available then for a price you'd want to pay.

Might just leave well enough alone then. I just thought the system worked better with R12. But it's definitely not worth it to replace all that stuff again just for a marginal increase in performance. Thanks for the advice

Just for reference the only new replacement service valves available for our system is 4 seasons parts numbers 12778 and 12780. They are for rotolock compressors but can be used with tube o ones with adapters.

No doubt R12 is the better option, but economics is working against it now. My 134a runs pretty stinking cold on the highest setting. Find myself having to back that off after a bit. I do see a rise in the temp when sitting at a light or in traffic, but planning to get a fan shroud soon to help with that.

kansasboy001 wrote:Might just leave well enough alone then. I just thought the system worked better with R12. But it's definitely not worth it to replace all that stuff again just for a marginal increase in performance. Thanks for the advice

Just for reference the only new replacement service valves available for our system is 4 seasons parts numbers 12778 and 12780. They are for rotolock compressors but can be used with tube o ones with adapters.

When I redid my system sprung for new service valves and they leaked. Yanked them and didn't replace. Just another potential leak waiting in sidelines.
They weren't cheap either!

I'm a novice with the AC system of my Cherokee Chief. The previous owner converted the system to 134. The system needs to be recharged, I did before with other vehicles that I own but on this, I don't know where is the low-pressure port. Is the right or the left port? Also, do I need to open the values. My guess is yes but not sure. Can you help me with that?

Thanks for the help!

Sent from my SM-G960U using Tapatalk

Low pressure would be the bigger hose coming from the evaporator. The high side goes to the condenser in front of the radiator.

The valves are three position. Where they are now should be the normal position. A turn or so CW, I think, is the service position and opens the service port to allow charging. Fully CW isolates the system from the compressor so it can be removed without venting the rest of the system.

So you hook up the gauge set and turn the valves in a turn or so, evacuate it if you're going to, charge the system and back the valves out again.

I wish i could find a can or two of r12. I had a guy with like 30 lbs bottles and cans all over his garage.. id pay 25 to 30 a can.. then he just stopped responding. I filled it up twice. First time with 2 cans when i got the jeep. 2nd with 1 can. That was almost 2 years ago and its still blowing cold. But i can tell it needs more on a really hit day if im atanding still it doesnt get very cold like it used too.

I know where the leak is too. One of the hoses has a buldge and i can see it leaking... Not sure how to patch that.. i almost thought of taking a hose clamp and some rubber and clamping it like a leaking pipe... but i dunno if thatd work.

I did use that butane stuff once.. and it actually worked.. but after i read it isnt compatible with butyle rubber hoses i let it all out if the system like a air nipple on a tire then filled it with r12.


Not sure how one comes accross these cans other then asking on craigslist if someone has any i could use lol.. cant buy it on ebay without a license

[quote="r_torres"]I'm a novice with the AC system of my Cherokee Chief. The previous owner converted the system to 134. The system needs to be recharged, I did before with other vehicles that I own but on this, I don't know where is the low-pressure port. Is the right or the left port? Also, do I need to open the values. My guess is yes but not sure. Can you help me with that?

Thanks for the help!

Sent from my SM

Just a suggestion to check for leaks first! I guess adding Freon counts.

Xplitive wrote:

r_torres wrote:I'm a novice with the AC system of my Cherokee Chief. The previous owner converted the system to 134. The system needs to be recharged, I did before with other vehicles that I own but on this, I don't know where is the low-pressure port. Is the right or the left port? Also, do I need to open the values. My guess is yes but not sure. Can you help me with that?

Thanks for the help!

Sent from my SM

Just a suggestion to check for leaks first! I guess adding Freon counts.

If you have a york compressor the low pressure is the port on top. Not sure on the sanden

candymancan wrote:I wish i could find a can or two of r12. I had a guy with like 30 lbs bottles and cans all over his garage.. id pay 25 to 30 a can.. then he just stopped responding. I filled it up twice. First time with 2 cans when i got the jeep. 2nd with 1 can. That was almost 2 years ago and its still blowing cold. But i can tell it needs more on a really hit day if im atanding still it doesnt get very cold like it used too.

I know where the leak is too. One of the hoses has a buldge and i can see it leaking... Not sure how to patch that.. i almost thought of taking a hose clamp and some rubber and clamping it like a leaking pipe... but i dunno if thatd work.

I did use that butane stuff once.. and it actually worked.. but after i read it isnt compatible with butyle rubber hoses i let it all out if the system like a air nipple on a tire then filled it with r12.


Not sure how one comes accross these cans other then asking on craigslist if someone has any i could use lol.. cant buy it on ebay without a license

If you already have an intact and working system, It’s not that bad to rebuild.
A couple of things to remember though are coldest temps achieved at low blower speed. For improved efficiency, I’m running an electric fan with a pwm and ac trigger controller. have no doubt a good clutch fan would work as well though, the one I took off was definitely moving air through the grill.
R134 is $5 a can if it helps..

Everything on my system works its just the larger hose by the compressor has a buldge and leaks slowely. All id need to do is replace that hose but i wouldnt know where to start.

Thats why im wondering if a clamp on some rubber and clamp the bukdge if thatd help but probly not lol. Even though its buldging and leaking from it it litterally took 2 years and its still blowing cold so it isnt that bad of a leak oddly