Auto AC. R12-R134a conversion... oil?

[Little Red]

Hi everyone,

I’m not an AC techie, nor a chemist or biologist, so I have become completely lost in the various internet sites and conflicting information. All I am trying to do is convert my auto AC from R12 to R134a and would appreciate some advice.

Car is a 93 Corvette and was running R12. The compressor (Denso 10PA20C) developed a front shaft seal leak, so in my infinite (or not) wisdom, I decided to totally rebuild the compressor with new bearings/thrust washers/seals etc. No problem so far, the comp is on the bench in a 100 pieces and thankfully no signs of undue wear or any particle contamination and it should go back together ok.

Now…!!!, not knowing anything about AC, my info comes from the net and here is where I’m stuck/confused.


......what type of oil do I use for this compressor with a R134a retrofit?

I’ve read that it should be PAG46 (Denso’s recommendation for the comp), I’ve also read that it should be a 100 viscosity Ester oil (so that it doesn’t react with any residue oil left in the system), another opinion suggests a PAG ‘d-capped’, what and why the later is I don’t know.

In a fleeting moment where I thought I understood what was needed, I went and bought a liter of ‘Emkarate RL2000’ that the garage salesman waved under my nose. I’m now not sure if this is the correct oil and particularly if it is the right viscosity… the product sheet says ISO68 !?

Another web contradiction I’m coming across is whether it’s a good idea to flush the system or not, if so what with and how?

Any opinions/suggestions please?

Many thanks.

PS: I know I need new R134a compatible seals, gauge/charge adaptors and I’m fitting a new accumulator/drier for good measure. I’ll also have the system recharged at 60-70% of R12 recommendations

[sedgy]

hi little red ,
just to add to your list there is a pressure test , a leak test, the system needs evacuating, then gassing up ? are you registered ?
you may be better advised to find a repitable garage ? but all the best in your venture.

[Little Red]

hi little red ,
just to add to your list there is a pressure test , a leak test, the system needs evacuating, then gassing up ? are you registered ?
you may be better advised to find a repitable garage ? but all the best in your venture.

Hi sedgy,

I didn't know about a pressure test, what is that one?. It's already evacuated (prior to stripping the compressor). I was planning on getting a good long vacuum applied as a leak test prior to regassing.

I'm in Spain, like you, but unfortunately in my area there isn't a decent AC shop. When I had the R12 evacuated I noticed that they were purging into the same machine they use for R134a and I didn't think that to be right! (unless it is ok?)... so I'll find another garage for regassing.

Don't know what you mean by 'registered', I'm not an AC Tech.

[radekklimat]

Replace the filter dryer, pull well and then fill the vacuum system R409A
This is a replacement for R12 in the same quantity.
The problem with the remake is that in addition to replacement of all rubber parts will not know how much 134a fill volume falls because less of it

[monkey spanners]

Be better off putting 5gs mineral oil back in and running it on a R12 drop in such as R413A, unless you plan to change all the flexi hoses too.