Just use R134a?

If you were charging up an old chevette I would just top it off with 134a, however, for a machine that is collectable some day, and extremely expensive to replace parts on, I would in no way just top off the refrigerant with 134a.

R12 and R134a are different chemical compounds with different densities. Mixing them will still provide heat exchange, however, oil dilution/miscibility will become your issue, not to mention acids that will form with the mixing of these two refrigerants. The oils that these two refrigerants require are radically different. R12 (A Cloro Florocarbon (methane) - contains clorine atoms) requires a polar (mineral based) lubricant to properly dilute at the right levels to be circulated through the systems components. R134a (Floro carbon (ethane) - no clorine) requires a non-polar (ester or PVE) lubricant. Oil circulation and dilution is very important in a car, as it relies on this entrained lubricant to properly lubricate the bearings and pistons in the compressor.

You basically have two options here:

First, try and find some R12. It is still available and the price isn't so bad now that the demand for it is nearly zero. Top off the R12 and you will be in good shape.

Second, you need to evacuate the system, remove the compressor and pour out all the oil you can. Hook everything back up, draw a vacuum on the system, add the new R134a compatible lubricant and refrigerant and you are good to go. R143a will not give you quite as good of cooling characteristics in a R12 system because of the energy density of R134a being less than R12, but it will work. You may also realize that you need to top off 134a more because its molecules are smaller than R12 and will leak out faster if you do have a leak.

My 348 needs a little refrigerant now too, I'm going to get some R12 and top it off, when I do my engine out service I will probably go ahead and convert the system to R134a.

Dave

 

Dave is on the money.

But, let me throw this out there for you..........

Two weeks ago I looked a mate's a/c in his old Toyota L/C. A/c has not worked for over 10-12 yrs. Its an old R12 system. R12 gas is illegal and obsolete here in Australia now.

I borrowed some R12 a/c gauges off a friend and put them on. There was no gas in the system, of course.

I had an adapter for R134A so I put bottle pressure R134A in the a/c system and soon found leaking orings on top of the compressor. They were flat and hard and were leaking. I replaced ALL 4 orings on the compressor and all the orings on the a/c hoses into the compressor and drier/condensor.

I vacced it down for a few hours, shut it off and it held vaccum for another hour or so.

I usually vapour charge the system, but my Brother was there and he likes to liquid charge the system. So he did that, using scales to put the right amount of gas in. We started her up and the a/c was ICE cold.

The pressures were good, no leaks visible anywhere. The a/c was around 3c in the vent. Which is beautiful for R134A. Any colder and the evaporator would probably ice up.

We also found the a/c condensor fan was jammed up against the front grill, which was pushed back onto it. We had to cut away the grill and it started spinning again.

I talked to my friend at work yesterday and he said the a/c is still ice cold and working great.

Just some food for thought. Good luck.

 

very impressive Papster!!

 

PAP IS THE MAN !

 

Well, can't help you much in the Netherlands - got a customer in Sweden (Nibe), but that won't help much either.

I know here some of the local auto parts stores used to offer a 134a conversion kit that included the adaptor, an oil charge that worked to "blend" the polar and non polar lubricants such that they would work OK together. It also had seal conditioner for the o-rings that would cause them to swell some in order to seal better. I installed a couple of these kits and never had any trouble with the systems.

At the absolute minimum to use that kit you need to evacuate the R12 and pull a vacuum on the system before adding the new lube/conditioner and refrigerant. There are various cheap vacuum pumps you can buy. You can bleed the system down to no pressure and install the kit, but I would pull a vacuum if you can.

I have done some pretty interesting stuff with refrigerants too, as that is what our company does, we build compressors for refrigeration and air conditioning equipment and we sell all over the world with compressors for use with about all refrigerants known to man. Your only concern might be shortening the life of the compressor a little if the bearings don't get completely lubricated. I imagine in the Netherlands it doesn't get too hot, so loading on the bearings might not be too bad, and you may be OK.

 

Cheers fellas!

 

PAPPY has done it again

 

Pappy strikes again!