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In my quest to make my car compatible with the HKS V-Mount a/c lines, I've dug really deep into the JDM a/c parts catalog. I don't have everything concrete and i'm not sure I ever will but hopefully this will help someone in the future.
My car: 1992 build FD, chassis 114381.
A/C Components on my car and their comparison to USDM parts
Compressor: Is marked DENSO. R12 fill. The lines that mate to the compressor on my car also mated up to a USDM R12 Denso Compressor. Quite possible you can use a USDM compressor on this early JDM chassis.
Drier: Not DENSO. I purchased a UAC drier part # 1225C cataloged as a RX7 Denso drier and it will not work with the 1992 lines. The line going into the drier does have the sight glass, however.
Lines: These will be specific to the early JDM chassis, due to RHD orientation and line/fitting sizes. It may be possible to use a US line from the compressor to condenser, or drier to condenser but that's it.
Condenser: I was sold a USDM DENSO condenser from tomsn16, this condenser matches the condenser from my 1992 perfectly. Lines screw in, everything bolts up the same.
Pressure Switch: The JDM 1992 and 1996 switches are identical, I do not have a US switch to compare.
Evaporator: This will be JDM, and early JDM specific due to the RHD orientation and line/fitting sizes.
R134 JDM A/C Components and how they compare to the early/R12 Components
R134 appears to have been installed in mid 95 & later JDM models. Besides the pressure switch, and the electrical components attached to the evaporator, none of these parts will cross over to the early JDM model. Its all or nothing. Every line/fitting is a different size and/or type, similar to the differences between USDM MANA and DENSO systems.
HOWEVER, parts are still available for the R134/late model systems in Japan. I was able to purchase a few lines brand new, a brand new condenser, and compressors are available as well. I will be installing an entire JDM R134 system in my car and so far everything will work. The only question left is the evaporator which I will report back on later.
Why did I go through all this trouble to make my car fit a few lines vs making a few lines fit my car? I'm stubborn, and I like tinkering. I wanted everything to bolt and work as OEM. If I need a replacement for anything it is somewhat easy to get and no need to have another custom line made or whatever the case. Plus its all designed to use R134, which is also readily available.
JDM 1992 R12 Evap on the left, JDM 1996 R134 evap on the right. Plug and play in the car. The connector plugs right in, same wire colors. Two bolts hold it in. Drop the glovebox completely, 2 screws. One nut on the very top of the evap and one at the very bottom. Super easy for an evap swap.
The difference is in the lines. JDM 1992 R12 on the left, JDM 1996 R134 on the right. Again, the R134 evap will plug and bolt in to the car but the R12 lines will not work.
Last edited by AE_Racer; Aug 15, 2019 at 07:24 PM.
Again, the lines are not compatible between the two. However, they bolt to the car the same, the electrical plug in is the same, the clutch and pulley are the same.
R12
R134compressor, pics stolen from DaleClark. Its already in the car, forgot to take pics I have seen pictures of a few other compressors with the matching 442500, followed by -4570 and -4572. Those looked identical to this one.
Last edited by AE_Racer; Aug 15, 2019 at 07:28 PM.
So I wanted to add to this thread... as my friend @AE_Racer and I came to find out on my car...
It appears the 1993 JDM RX-7 came factory R134a. Came to find this out after having to replace the drier and the expansion valve on the evaporator. Turns out if you order 1993 USDM RX-7 parts, you are going to get R12 variants and the ports will not work. If you order any year with the R134a, you are going to get it to work. Also, the expansion valve is interchangeable with a number of other cars... namely a Lexus ES300. Turned out to be a Denso Expansion valve #447500-0031. I was able to source it looking under Lexus at a local auto parts store. Our A/C Thermoswitch that sits on the evaporator also is interchangeable with early Mazda MPVs. I'll do a bit more digging, but looks like it may have also been used on a number of other Japanese brands/models. So even when you think a part is no longer available for the RX-7... it might just be the same part for a newer car.
Anyways... now my A/C is working like new again and its so cold even in stop & go traffic with the Florida heat of 90-95 degrees... I still have to turn the fan setting to 2 unless I'll freeze.
Did the evaporator construction look much different between the R12 and R134a versions? I've got an early JDM car as well which I'll have to piece together an AC system for as most of it is missing... I remember reading somewhere that many cars which moved from r12 to r134a also changed the evap construction as the R134a has a lower specific heat?
I've got an R134a compressor in a box somewhere I can swap on, just hoping the evaporator / expansion valve will be all good? Don't want to have to muck around sourcing those parts. I can make / have made the lines, no to stressed about that.
@ZacMan if you are just changing the compressor, you shouldn't have to worry about the rest of the system. It will just be converted to run R134a versus the R12. I can tell you that the evaporator and everything else in the system is different between the R12 and R134a cars due to the port sizing. All the JDM cars were Denso units so you won't have to worry about sourcing MANA parts.
So I wanted to add to this thread... as my friend @AE_Racer and I came to find out on my car...
It appears the 1993 JDM RX-7 came factory R134a. Came to find this out after having to replace the drier and the expansion valve on the evaporator. Turns out if you order 1993 USDM RX-7 parts, you are going to get R12 variants and the ports will not work. If you order any year with the R134a, you are going to get it to work. Also, the expansion valve is interchangeable with a number of other cars... namely a Lexus ES300. Turned out to be a Denso Expansion valve #447500-0031. I was able to source it looking under Lexus at a local auto parts store. Our A/C Thermoswitch that sits on the evaporator also is interchangeable with early Mazda MPVs. I'll do a bit more digging, but looks like it may have also been used on a number of other Japanese brands/models. So even when you think a part is no longer available for the RX-7... it might just be the same part for a newer car.
Anyways... now my A/C is working like new again and its so cold even in stop & go traffic with the Florida heat of 90-95 degrees... I still have to turn the fan setting to 2 unless I'll freeze.
Hold up dude, I need to stop you right there before some people get the wrong idea. I'm looking at the Japanese FD manuals right now and know beyond any doubt that the changeover from R12 to R134 was in July 1993, in accordance with Japanese law enacted in May 1988 (Showa 63) as I learned when translating the corresponding section for the Eunos Cosmo last week. Everything was approved/ratified in January 1989 (Heisei 1). Anyway, the Japanese FD Maintenance Supplement, dated July 1993, details what can and can NOT be used between the two systems, even down to the Charging Port threads. R12 High side is 3/8-24 UNF, Low side is 7/16-20 UNF, both being Union Nut Type. R134 high side is 16mm OD, Low side is 13mm OD, both being Quick Joint Type (AKA Quick Connect.).
Bottom line is that FDs built in July 1993 will be R134 no matter where in the world you are. It's roughly akin to "94 spec" here in the US.
I think I'm lost by your post? I think we are stating the same exact thing? 93 JDM is akin to 94 USDM RX-7s that used R134a. My issue was that any 93 USDM parts were for R12 which led me on the odyssey to find out that the JDM 93's were in fact R134a already.
95 is when it became mandatory in the US. This makes sense that they changed it earlier for the Japanese cars with a different government mandated switch over.
Also remember '94 and '95 is model year, they were built and sold earlier than that.
I have about four sets of JDM a/c equipment. I have not been actively selling, as I have not got the bins sorted out. If you need a piece give me a DM.
I think I'm lost by your post? I think we are stating the same exact thing? 93 JDM is akin to 94 USDM RX-7s that used R134a. My issue was that any 93 USDM parts were for R12 which led me on the odyssey to find out that the JDM 93's were in fact R134a already.
Actually, it would be more along the lines of what Dale Clark said. a 7/93 build would be a 1994 model, hence why you had to look for 1994-spec parts. One of the few instances where things like up chronologically between North America and Japan for one reason: Mazda doesn't reinvent the wheel without a good reason.
94 RX-7's in the US had R12. 95's had R134a.
Are you sure about that? It's been awhile since I looked in the USDM parts catalogs, but it wouldn't make much sense from a manufacturer's perspective to stagger the conversion to R134 when the only regional difference is the Evaporator location and its lines being longer for LHD models. Again, "don't reinvent the wheel" applies here. Plus, the July 1993 Maintenance Supplement for Japan is pretty adamant about R12 never being used again.
For comparison, my first car was a 1995 Mitsubishi Mirage (built 11/1994). This generation (93-96 in the US, 92-95 in Japan, production began in 10/1991) made the jump to R134 for US model year 1994 as well. Coincidentally, airbags were also phased in starting in 1994 for driver and 1995 for passenger side. Since this was their ecobox model, it got airbags last while a higher-end model like the FD or GTO (3000GT) would receive all the new "toys" first, all despite being in advance of the 1996 requirement for airbags in the US.
Anyway, back to the matter at hand. Realistically speaking, to do a retrofit in a R12 car the correct way, it sounds like line adapters for using the R134a Receiver-Drier and Compressor, and O-rings for each connection are all that's needed.
My '94 R2 has R12 from the factory, no questions about it. All '94's I've ever seen have had R12.
Many US cars had the AC system installed at the port in the US, the "MANA" AC system.
Dale
That makes sense, things were quite strange when it came to A/C in cars until around 1997/1998 when it became more of a standardized feature instead of an option. The conversion from R12 to R134a was quite a big matter, yet it seems the dividing line is still as blurry as ever here in the US. Japanese cars in the US added yet another layer of confusion to the mix with either factory (NipponDenso) for Dealer/Port (MANA) installed systems, turning anything with A/C into a completely chaotic, unserviceable mess that only a dealer could fix...maybe. No wonder the RX7club came to be...
Got a feeling the very first thread here was "Why does my a/c suck?"
Anyway, once I'm finished with the Eunos Cosmo, I'll be turning my attention to the FD in order to give this proper attention.
I'm so glad that I came across this thread. I recently moved to Florida and my JDM FD should be getting sent here soon. I've been on the hunt for info for the A/C system because it's never produced cold air in the 3+ years I've owned it and I just now started looking into my options. Any idea on the pricing for buying the 93+ system from Japan?
It can be tricky finding RHD AC parts from what I understand.
Hands down the most common problem with AC is a leak. You really need to figure out where it's leaking first to know what you need to fix or buy. A good AC shop should be able to sort that out quickly.
But it is the service ports also in different location for JDM? I read that on USDM they are by the turbo side, but mine, 1993 JDM, seems to be on the intake elbow side.
In my quest to make my car compatible with the HKS V-Mount a/c lines, I've dug really deep into the JDM a/c parts catalog. I don't have everything concrete and i'm not sure I ever will but hopefully this will help someone in the future.
My car: 1992 build FD, chassis 114381.
A/C Components on my car and their comparison to USDM parts
Compressor: Is marked DENSO. R12 fill. The lines that mate to the compressor on my car also mated up to a USDM R12 Denso Compressor. Quite possible you can use a USDM compressor on this early JDM chassis.
Drier: Not DENSO. I purchased a UAC drier part # 1225C cataloged as a RX7 Denso drier and it will not work with the 1992 lines. The line going into the drier does have the sight glass, however.
Lines: These will be specific to the early JDM chassis, due to RHD orientation and line/fitting sizes. It may be possible to use a US line from the compressor to condenser, or drier to condenser but that's it.
Condenser: I was sold a USDM DENSO condenser from tomsn16, this condenser matches the condenser from my 1992 perfectly. Lines screw in, everything bolts up the same.
Pressure Switch: The JDM 1992 and 1996 switches are identical, I do not have a US switch to compare.
Evaporator: This will be JDM, and early JDM specific due to the RHD orientation and line/fitting sizes.
R134 JDM A/C Components and how they compare to the early/R12 Components
R134 appears to have been installed in mid 95 & later JDM models. Besides the pressure switch, and the electrical components attached to the evaporator, none of these parts will cross over to the early JDM model. Its all or nothing. Every line/fitting is a different size and/or type, similar to the differences between USDM MANA and DENSO systems.
HOWEVER, parts are still available for the R134/late model systems in Japan. I was able to purchase a few lines brand new, a brand new condenser, and compressors are available as well. I will be installing an entire JDM R134 system in my car and so far everything will work. The only question left is the evaporator which I will report back on later.
Why did I go through all this trouble to make my car fit a few lines vs making a few lines fit my car? I'm stubborn, and I like tinkering. I wanted everything to bolt and work as OEM. If I need a replacement for anything it is somewhat easy to get and no need to have another custom line made or whatever the case. Plus its all designed to use R134, which is also readily available.
If you have any questions feel free.
I have a 1993 usdm and need the whole ac system minus the evap. Condensor, compressor and lines/hoses Text me 832-638-4380
I have seen pictures of a few other compressors with the matching 442500, followed by -4570 and -4572. Those looked identical to this one.
