AC question

[strupgolf]

On 1989 944S2 cars, are they R12 or R134? How can you tell if your car has been converted to 134 if it has? And, is recharging a DIY job? Thanks.

[HondaDustR]

Originally Posted by strupgolf

On 1989 944S2 cars, are they R12 or R134? How can you tell if your car has been converted to 134 if it has? And, is recharging a DIY job? Thanks.

I think cars didn't change over to 134 until 92 or 93. There should be a sticker that gives the information on refrigerant capacity. If it was converted correctly, there should be some quick connect fitting adapters installed on the schraeder valves to allow you to connect the 134 charging hose directly. Otherwise, who knows. Easiest way would be to get your hands on some R12, but most people won't sell it to you without a EPA certification (which actually is not hard to get). R12 is getting harder to find and it won't sell cheap.

I can't remember off the top of my head the oil compatibility issues of what doesn't work with what when converting, but generally, it requires recovering any existing refrigerant (you know...), draining as much existing oil as possible, flushing out the system (depending on how clean it is already, what oil you're going to use, and how anal you are...it is complicated as there is a TXV in the system and you would have to remove it prior to flushing), replacing o-rings on any disassembled connections, leak testing with nitrogen (kind of optional as most people don't have the equipment, but is a timesaver if something leaks), fixing any leaks found, adding new oil that will not break down in the presence of CFC and mineral oil residue (want to say it's PAG oil, but I don't remember...you cannot use mineral oil, as it is not miscible with HFC refrigerants and will not return to the compressor properly), replacing the receiver drier, evacuate the system, charge to about 8-12 deg F of subcooling on a hot day. If you don't leak test with nitrogen, use a UV sensitive oil to help find leaks after the fact. Checking if the system holds vacuum will tell you that it is dry and that there are no major leaks, but it will not ensure it is completely leak free. Leak testing with vacuum is the same as leak testing with 14 psi nitrogen...not very useful.

[bnoon]

You want to use ester oil on converted systems. PAG is for 134 systems that have always been 134. I have not found it hard at all to get r12 though, just more spendy each year. This may be the year I finally convert a.car though.

[Gawernator]

It was apparent my 944 was converted because of the different Schrader valves for charging with refrigerant.

[HondaDustR]

Originally Posted by bnoon

You want to use ester oil on converted systems. PAG is for 134 systems that have always been 134. I have not found it hard at all to get r12 though, just more spendy each year. This may be the year I finally convert a.car though.

That sounded familiar, but I wasn't sure, as I thought polyolester and chlorinated refrigerant residue were a bad combination in stationary equipment, but quick research does not indicate any problems. Maybe it was alkylbenzene, but that's a pretty popular choice for low temp R22 systems.

Ebay always has some r12 kicking around somewhere, but not everyone will sell it to you without certification.

[John_AZ]

Griffiths, aka Pelican member kuehl has a lot of information on his web site.

AIR CONDITIONING HELP HOME PAGE,a/c,ac,air,air conditioning,barrier hose,Behr,Bosch,compressor,compressors,condensers, condenser,condensors,drier,driers,dryers,evaporato r,evaporators,freon,Griffiths,improvements,Kuehl,N ippondenso,Porsche,r12,r134a,San

POE 100 esther is his preferred oil to use- mixes with old AC oil unable to flush out in the expansion valve and evaporator.



quote " is this a DIY job?"

Yes with the tools, guages, electronic leak detector or dye, seals and a decent leak down pump--NOT a cheapy venturi Harbor Freight pump.

You can also improve the cooling of R134a with a "dual tube condenser".

Griffiths sells one and v2Rocket_aka944 has built a few.

J_AZ

[strupgolf]

After looking at the reply's, I'm thinking I'll have it checked out at a shop. Sounds like a job I'm not at all familiar with. Thanks for all the replies.