3 years ago, I converted my car's leaky A/C system to r-134a with little success. The system leaked terribly with the 134 and for about 2 years I gave up on having a working A/C system. This summer, I started working on sealing up the system again, and I have it to the place where it will hold a charge for a decent period of time. However, the 134 just doesn't seem to work with my system as well as the r-12 did(possibly because I still have the r-12 oriface tube). Luckily, I stumbled across a keg of r-12 at a friend's shop, and he said I could have it.

Seeing as how I am getting this r-12 for free and will probably never have to pay for refridgerant as long as I own my car, I have decided to convert back to r-12.

I have a few questions:

1. I did the 134 conversion 3 years ago. Has the PAG oil probably leaked out by now? If not, how can I remove the PAG oil from my system?
2. Should I replace the cannister?
3. Can I still purchase the mineral/ester oil, and how do I add it to my system?
4. Can I still purchase the r-12 tubing to charge my system with my "keg"?

Any other comments and advice would be much appreciated.

 

To get rid of the PAG oil, I would pull a GOOD vacuum. I mean over do it, and then some. Maybe even cycle the system, then pull the vacuum again, to "push" out any PAG oil that may be "stuck" in dead spots in the system. New compressor & condensor?

Just a thought. I personally don't know of anybody that has converted it back.

 

I wasn't sure if simply a vaccum would do it...exactly how bad is it if there is a little PAG left in the system?

 

Flush, Flush, Flush...

Then flush it again.

Start with brake cleaner as it is cheap and readily available and finish up with commercial A/C System flush. (Everco etc..) Use only the flush in the compressor as the brake cleaner may effect compressor seals.

If by canister, you mean accumulator/drier, then yes. It has a desiccant in it that is ruined by now. Also replace the orifice tube as it catches the garbage.

Mineral oil is still available at good parts houses; don't know about Vato Zone or if you frequent such places. It can be added directly to the compressor after flushing (about two ounces) and the remainder to the new accumulator immediately before installation. Don't uncap the new accumulator until right before installation and it should be the last thing installed. The system should begin evacuation as soon as the last fitting is tight.

R-12 Manifold sets are still available. A local reputable auto parts store will probably have them or can get them. Again, can't speak for such places as Vato Zone. I strongly encourage the use of a manifold set and the monitoring of both high and low side pressures. Suicide taps are at a minimum, dangerous.

Be careful about your free refrigerant, there is much “black Market” refrigerant that is loaded with propane and other flammables. It can be loaded with moisture and other impurities as well.

No amount of vacuum will remove oil from a system, a vacuum will only remove those materials that will be or become a vapor at 0 PSIA at ambient temperature, oil will not.

 

I converted mine to 134 last year (believe it or not the factory system lasted that long...lucky me) this thing leaks constantly not from the seals but from the swedged fittings. I'm on my 3rd hose set and they all leak from the same fitting at the witness hole for the swedging. I guess we just service it up every year. Maybe I need to buy a hose set from someone other than Advance Auto Parts and NAPA they use the same sorry manufacturer for ac parts.

 

So...let me make sure I have this right...
1. Flush compressor
2. Add oil to compressor
3. Add oil to accumulator
4. Install accumulator
5. Pull vaccum on system
6. Charge w/ r-12

Am I missing anything?

 

You need to flush the hoses, the condenser and the hardest thing to flush without removal – the evaporator.

 

How do I do that....is there a product I can buy to flush it with?

 

I don't think you can flush the compressor just the lines, evaporator, and condenser. I have a CD tutorial it says don't flush the compressor. I would talk to someone who knows ac systems.

 

I run HC-290 in my A/C systems, I am not the least bit scared of it. Once the moisture is removed, it works great. R134a and R12 are both HIGHLY flammable when mixed with refriderant oil anyway. They both can errupt into a flash fire as well. My HC-290 systems blow around 35-40* at the vents, idling in traffic, and cycle continuously. Out of 1 minute, the compressor runs about 15 seconds. On a 105* day outside with 70% humidity, it is nice when the compressor only has to run 1/4 of the time to keep it cold enough inside the vehicle to hang meat. R134a sucks, period, end of story.

 

Dude, you're going back to R-12? You are my friggin' hero. Let us know how it turns out.

 

I use HC290 and it gets colder than R12, people are just too afraid to use it. It is used like crazy in Australia where it is HOT and Humid. I have to switch everything that I convert over to thermostatic type cycling switch. At the typical 40 PSI (Road Speed) that an A/C system runs at, HC 290 boils at about 20*F, at 60 PSI (IDLE) it boils around 40*F.

 

Still wondering...how exactly do I go about flushing these components...is there a kit?

 

I bought an aerosol kit from NAPA and I beleive it said not to flush the compressor.

I beleive there is an oil that is like a neutralizer that is compatible for retrofits.

When you retrofit to 134 all you did was remove the R-12 and flush the lines,eveporator and condenser, replace the 'O' rings, accumulator and orfice tube and installed the recommended amount of PAG oil in the accumulator. Then you vacuumed it down for about 45 mins. and then serviced with R-134A. so why can't you just reverse the procedure. I don't see why it would be that big a deal. Since the system is open pour as much oil as you can out of the compressor or replace it.

 

If you leave PAG oil in your system, R-12 will turn it into tar.
http://www.autofrost.com/hotshot/index.html

If all you did when you converted to 134A was what you said, then you used a flawed procedure. (Maybe that added to the reduced performance or "little Success" of your conversion) If you want to use the same flawed procedure to convert back, of course you can.

A reputable parts house will have a liquid A/C system flush you can pour into your components and blow through with dry shop air.

To do it right and have a clean conversion, You MUST flush it completely. The compressor holds a lot of oil that must be flushed as well. Flushing an R-4 compressor is not too complicated. Add flush, shake, rotate hub, pour out, repeat until clear. Then add oil and rotate through the compressor.

If you don't flush it, yes it will cool just fine (maybe) - for a while anyway.

I just did a quick search and found http://www.f11view.net/misc/ac_retrofit_problem.html. It appears to have some good information.

As far as the magic oil, I don't know of such a thing but it sounds like snake oil to me.

I have opened up converted (to 134a) systems that were not flushed correctly and found the tar remains of broken down oil. I have replaced compressors that died from lack of lubrication because of refrigerant contamination (r-12 added after a 134a conversion) when service fittings were not changed.

Neither R-12 nor 134A are flammable.

 

The flush doesn't sound too bad...i just didn't know what to do

 

I was not sure if you could flush the compressor. I based my opinion on flushing a compressor on a tutorial CD I have on AC system repairs. At the time I converted my system I had to replace my compressors because of age. I know there are probably thousands of systems converted without replacing the compressor and probably the reason for the unreliability of the conversion. I also believe the condenser, and evaporator passages on a dedicated 134A system are much smaller and more plentiful, giving the system more efficiency.

TexasSilhouette, The websites you refer to have a lot of good info.

I like your avatar, being a hunter myself thats cool.

 

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