I have a 85. When I bought it the air conditioner did not work. It had been switched over to R134 from R12. I had the system serviced. Vacuumed and charged. The first season it worked great, the second season it worked OK. This season it did not. So, I just had the system recharged again and it works fine. It was decided that the system did not need to be vacuumed because there was some coolant left in the system. Cost was $150.00
I understand, arguably, that R134 in a R12 system is a leak waiting to happen.
My thought is to use the disposable bottles available at an Auto Parts Store the next time. What are your thoughts? How do you know your not overcharging?
Thanks,JW

 

There is a gauge right on the can from what I understand.

 

R134a installed properly in an older R12 system should not be a problem.

It sounds lie you may have a small leak, possible from a seal that has dried up. Did you have a leak detector dye installed when the system was recharged? A detector dye is necessary to find leaks so they can be found and fixed.

I would avoid the DIY stuff when it comes to A/C work. If you don't have experience with A/C systems and don't have the right tools, it's easy to really mess up the system.

 

When changing over refrigerant from 12 to 134a the oil is the bigger issue. The "retro-fit" also consists of installing the 134a service valves to prevent 12 from re-installed. It is common to "top off" refrigerant vs. recover, evac, & recharge. The r12 compressor oil doesn't work well with 134a usually causing compressor failure. Mixing to refrigerants is not recommended, but it isn't the "mark of death" for the A/C system.

There probably a U tube video on how to charge or top off" You want a gauge on your DIY kit with a/c in max cold and fan on a high. Engine at 1500-2000 rpm gauge should read between 28-40 psi. and compressor should not be cycling. Outlet temp should be around 40 degrees. When both outside temp & humidity are both outlet temp can be higher and be ok.

 

Check your hoses, especially the one with that tight 180. It can develop a leak on the inside of the bend.

 

Hi

The old rubber hoses will need to be changed, the R134A will rip into the hoses and block your orifice tube. Get some new hoses made and replace the orifice tube and acumulator as well as the o rings get the green O rings, you can get the screw on R12 to R134A fittings on ebay.

Drain all the oil out the compressor turn the compressor shaft a few times when no more oil comes out fill it with the synthetic oil.
The R134A needs to be 80% of the R12 charge.
The label on the airbox will have the refrigerant charge in weight.
You will need a vacuum pump to remove air (air is 50% moisure)

I can post the oil type and quantity for retroifitting when i get home from work, as well as the R134A gas charge.

 

JW Drew,

Conversion from R-12 to R-134 can be done successfully however there are precautions. Several responses already have mentioned some such as the refrigerant oil incompatibility, the seals, etc. To do it correctly, you do need to remove the old refrigerant oil and replace the seals with the R-134 type (Green ones). You would want to replace the receiver/dryer also. With this much done there is a system flush solution which you can purchase that will clean out the tubes/tubing, condenser and evaporator. It must be flushed through the system. Once this is all done before you replace the refrigerant you need to evacuate the system. Then replace the refrigerant oil in the compressor and then the refrigerant. R-134 replacement into your existing system requires that you replace 10% less than R-12. The only other concern to keep in mind is that R-12 refrigerant is NON corrosive, while R-134 is corrosive. In the long term the compressor and other metal parts would/could be attacked and fail.

I hope I have not painted a dismal picture here but there are things to be concerned with. If I were to address this I would replace the compressor and receiver dryer with R-134 compatible units, check the hoses for age and wear and replace as needed, and replace all the seals. You may also consider replacing the pressure switch with a R-134 compatible unit. With this all done, recharge the system (after evacuating) and it should work very well.

Sledge_78

 

Thanks for your response's but your answers are kind of going in a different direction than I had hoped. Because of the expense of revamping or repairing the system, my thought is just to top it off every season.
Accordingly, I just am asking for your input on doing this DYI fashion.
Thanks, JW

 

Of course you can add R-134 Freon every season and technically it is not hard to do. However, you have a leak, leaks don't get better, or go away. Eventually you will have repairs, perhaps then you can follow some of the advice given here for successful R-134 conversions.

Sledge_78

 

The R134A is a blend, so topping up wont work you will have to do a complete evacuation and fresh charge.

You guys are lucky that you can buy refrigerant without a licence

With all your yearly smog testing why are you even allowed to use refrigerants when not qualified, I live in Australia and like most places in the world you need to be licenced to handle refrigerants.
Massive fines and you cannot import or buy refrigerants without a refrigerant handling licence.

So do it properly now and you will not have to touch your a/c for many years, i am sure that these laws will eventually come to the United States.

I did my a/c the correct way new hoses and, changed the oil and o rings new orifice tube and she is going strong 7 years later no leaks.

 

When I had my AC recharged, the shop used an electronic sniffer to find the leak in the evaporator. You don't need to deal with the dye.

 

GE makes a halogen leak detector (called a feret) which will detect and localize very small leaks which are not always apparent with dye (large leaks are a different story). Most well equipped A/C service shops will have one or something similar. They'll also have the proper vacuum and storage tanks to recover all the refrigerant and not release it into the atmosphere. Probably worth the money to let the licensed pro shops handle this one, although 134a, not being a chlorinated hydrocarbon, is not especially harmful to the ozone layer (ODF is 0), it still is a harmful greenhouse gas (~3000x more so than CO2) and should probably be collected when feasible.