DIY: R-12 to R-134a Conversion (How To)

turbogate

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Just checking on this again, I'm abotu to redo my system. I'm going 2jz which has a r134a compressor. Is it possible to still use r12?

Another important question, where can I still get the paralell flow condensor? I've gotten a few part numbers looking stuff up, one being 1039293 from american condensor. Is this right?
Great thread! Can anyone confirm this part number above or if anyone recently got a parallel flow condenser, can you share which brand/model condenser you got? Thanks all.
 

Doat

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I bought mine from Carpartswholesale.com part number P39293P. I recently replaced my condenser, compressor, dryer, and expansion valve following this guide for the most part and now my AC blows ice cold. You might have to bend a bracket that holds one of the suction tubes to make it fit but that's about it.
 

turbogate

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I bought mine from Carpartswholesale.com part number P39293P. I recently replaced my condenser, compressor, dryer, and expansion valve following this guide for the most part and now my AC blows ice cold. You might have to bend a bracket that holds one of the suction tubes to make it fit but that's about it.
Thanks for the info. Was it recent? I guess they are discontinued, they don't have it in the link provided and other places which pop-up with that part #
 

supranaut

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How different are the 89+ condensers? The ones ive found show only for 86/87 model years...
 

SupraClaou

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Can somebody help me on that :
I have a 2JZ swap. The 2JZ already has an R134 compressor on..., so the car's A/C system is left with only one charging port which is located on the hard line that is located on the right side of the condenser , since the other port was originally on the 7M compressor which is no longer on the car! What's the deal now with only one charging port??

Last , on a MA70 7M Supra mk3 ,which charging port is the Low pressure and which the High pressure ???
 

jetjock

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According to the TSRM and Cygnusx1 the LOW pressure port is located on the 7M compressor manifold isn't it? And the HIGH pressure port is on the hard line near the dryer/condenser...
Yes. The compressor manifold has two lines. One is suction and the other is discharge. The low pressure port is on the suction line.
 

Nick M

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The low pressure port can only be between the pressure drop and compressor. On any car. Some are convenient, like with an orifice tube, which we don't have.
 

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Working on getting the pictures back up. Should be all back up by Friday
 

Asterix

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(Back from the dead on Halloween!)

I'm collecting all the bits and bobs to get my A/C running again after so very long and I'm rather annoyed by the lack of definitive information about conversions from R-12 to R-134a. I'm not interested in turning into an ice cube, but I do want the system to last, be reliable, not leak, and do a good job of cooling/defogging during the cooler months in northern Virginia.

Perhaps someone who knows can address my concerns!

I bought a new Denso compressor, and it is labeled that it has ND-6 oil inside already, which is for R-12. Yes, I understand it's OEM spec, but R-12 has been super expensive and obsolete for over two decades now. I also bought a new receiver/dryer from Toyota and now I'm worried that the drying material inside is not R-134a compatible, again because "OEM spec for a 1988 car". Poo to that. To continue, I got a new expansion valve for my vehicle according to Rock Auto, so again I'm seriously concerned it's not right for R-134a.

From the linked Toyota TSB, I need to check and see if I have the replacement dryer or not. At least that question is answered.

The new condenser I bought (also directly from Toyota as nobody else has them) is serpentine, but there are 2 paths between ports. Is this considered "parallel flow"?

The peeps at Sanden have a guide about changing to R-134a (https://www.sanden.com/objects/retro.pdf) that includes a warning that changing the refrigerant will result in greater wear. I'm guessing their comment about discharge pressuring being 10-15% higher is the cause of the extra wear. Changing the refrigerant results in higher high-side pressure doesn't make sense to me. But, I'm an engineer, not a chemist. Still, 15% doesn't seem like enough for me to worry about.

I'm up for changing all the seals and o-rings anyway, so that's not a concern. All of mine are ancient, and definitely worth changing.

At least the two hoses to the compressor I bought claim they are compatible with both R-12 and R-134a. Kudos to Four Seasons! Toyota has discontinued one of them, so Four Seasons is the place to go anyway.

So, the compressor is full of ND-6 oil for R-12. The original post of this thread just talks about draining as much as I can, then putting in PAG oil for R-134a. Well, what about what's left? Thanks to the linked TSB I know the answer to this! Don't worry about what's left. However, the sight glass in the receiver will be worthless. I can live with that.
 

JDMMA70

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(Back from the dead on Halloween!)

Luckily I'm alive and well eh?

The new Denso compressors are compatible with R12 and R134a and have been R134a spec'd since the mid 90's. The Oil inside is most likely ND-6, all you have to do is drain the old oil out by turning the compressor over and turning the clutch a few revolutions. About 60-80mL of oil is in the compressor from factory in most cases, sometimes more. Once drained you can add either ND-8 (Pag 46) or Ester #100. The amount you add is dependent on what parts you replace.

The Denso driers, and TXV are all R134a spec, but compatible with R12 as well. The barrier hoses are different for R134a but to be fair as long as R134a oil is used even the old R12 barrier hose will be just fine.

Also your sight glass will be fine, they just wanted techs to black it out so it wouldn't be used to judge a vehicles charge. You can leave it be since it still aids in diagnosing certain A/C issues by being able to see the refrigerant flow.

As far as wear is concerned, increased wear was an issue when the gas was initially introduced, that was over 20years ago and improvements have been made on both the mechanical hardware and fluid side of things. Its true it runs at a slightly higher pressure than R12 but as long as your system conversion is done properly, you should be problem free for many years.

To make charging easy as my guide states, just charge 24oz or two 12oz cans into the system when you get around to charging if you are doing it yourself.

Hope that helps, let me know if you have any other questions.

P.S. its going to be very cold so don't worry.
 
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Asterix

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Thanks for the info, JDMMA70! I feel better about it all now. I want to do this right, not just so it works.

The Denso compressor definitely has ND-6 in it from the factory. I worry about putting incompatible lubricants together, but apparently it's not a problem.

I'm probably going to buy a 30lb jug of R-134a so I have enough for the rest of my life (and my second car). It looks like it's going to be phased out in a few years, so I want to avoid not being able to get it.
 

3p141592654

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The old oil is not miscible in R134a. So any remaining residue will have no ill effect, it will just sit as a blob somewhere in the system.
 

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JDMMA70

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Yes the condenser were different. They changed in September 1987 which is the same for all MK3s going forward. Looks like the condenser was discontinued. Hopefully Denso starts manufacturing them again.
 
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JDMMA70

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If you use the From 09/87 Condenser yes. If its the From 01/87 Condenser it may not fit or work 100% correctly.
 

plaaya69

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majestic47

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I did my conversion a few weeks ago on my 1990 JZA70 and am so happy to have cold ac! Great write up, Thank you for posting!

I changed the condenser, receiver, all of the o rings, and the gasket on top of the compressor. Same parts as used in the LHD same year of 7M, except maybe that gasket. I was able to get one at the local autozone.

The expansion valve I bought didn't match what came out. Tried to get another one from a different year, but the fittings were different sizes, so I reused the old one.

The compressor for the 1JZ was very difficult to fit through to get it out and back in. Fitting the square peg through the round hole.
 
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JDMMA70

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The expansion valve I bought didn't match what came out. Tried to get another one from a different year, but the fittings were different sizes, so I reused the old one.

The compressor for the 1JZ was very difficult to fit through to get it out and back in. Fitting the square peg through the round hole.
I'm glad to hear this is still helping owners. The expansion valve for the JDM cars are the same as the Pre89 bulb style expansion valves. I don't think they ever went over to the block style TXV overseas.

Yeah haha I've had to remove the compressor from a few 1JZ cars before and its not as easy as it is on the 7M cars.
 

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Just got my system back together yesterday morning. It held vacuum all night. Yay!

The Chinesium suction flex line didn't fit right and it took me a couple of hours to modify and wrestle it into place. This is the the Four Seasons 55987 from Rock Auto. The high-side line fit just fine (55988).

First, I had to bend and twist the rigid pipe end that connects to another hose in front of the condenser, as they put the block on rotated from where it needs to be. Then, on the compressor end, I had to elongate the bolt hole because it is offset from where it needs to be. And, I had to file off a little corner where it interfered with the service port. Sigh.

My cheapo Horror Fright manifold gauge is surely inaccurate for vacuum. I borrowed a friend's pump which he uses all the time to install residential A/C units. It pumps my gauge down to only 27" of vacuum, even by itself. I'm kicking myself for not just buying $120 gauges. When I get a chance, I'll compare my gauge to my pal's, though I'm sure his show close to 30" with that pump.
 
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plaaya69

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Just got my system back together yesterday morning. It held vacuum all night. Yay!

The Chinesium suction flex line didn't fit right and it took me a couple of hours to modify and wrestle it into place. This is the the Four Seasons 55987 from Rock Auto. The high-side line fit just fine (55988).

First, I had to bend and twist the rigid pipe end that connects to another hose in front of the condenser, as they put the block on rotated from where it needs to be. Then, on the compressor end, I had to elongate the bolt hole because it is offset from where it needs to be. And, I had to file off a little corner where it interfered with the service port. Sigh.

My cheapo Horror Fright manifold gauge is surely inaccurate for vacuum. I borrowed a friend's pump which he uses all the time to install residential A/C units. It pumps my gauge down to only 27" of vacuum, even by itself. I'm kicking myself for not just buying $120 gauges. When I get a chance, I'll compare my gauge to my pal's, though I'm sure his show close to 30" with that pump.
Funny because I was working on this yesterday and I had the same fitment problem on that Four Seasons suction hose too. I also ended up enlarging the bolt hole on the compressor end and installing that side first. It was much easier to wrestle the front end lol. The high side did install perfect with no problems.
 
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Asterix

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I wondered if they just made mine wrong or they were all wrong. You answered that question, plaaya69.

I took the hose to my bench vise, clamped down on the end block and twisted. No way I could do that without the vise and on my back under the car.
 
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plaaya69

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I wondered if they just made mine wrong or they were all wrong. You answered that question, plaaya69.

I took the hose to my bench vise, clamped down on the end block and twisted. No way I could do that without the vise and on my back under the car.
Well it does suck that that part did not fit the best, at least it is good to know I was not alone either and can warn others to let them know what they are in for. I did want to send that suction hose back but I was afraid that I would get another one with the same problem plus I wanted a/c working asap (have not been in a Supra with working a/c since around 2006 lol).

It is too bad that that suction hose looks to be discontinued but the discharge hose is still available new from Toyota. Maybe a custom made suction hose would have been better or if another company made a better replacement but I guess time will tell how these Four Seasons a/c hoses will hold up...
 

Asterix

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Indeed. My A/C hasn't worked since maybe 2003. I'm so happy to be getting to back. My 7-month winter car will be a year 'round car again!

I hear ya. It's been too long since I bought the hose to return it, but I thought seriously about buying another to see if another was any different. Yay for the forums and another like-minded Supra nut to find out this way.

Since my discharge hose was leaking, I needed another. ToyotaPartsDeal backs you up: suction is discontinued, but discharge is still available at $120-ish. Interesting.
 

Asterix

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Oh em gee! I have A/C! Vent temperature was about 58F with ambient of 95F, inside my garage. I'll take that.

I added another 70g of refigerant, putting the total just under 700g. It was hard to measure my cans and I didn't want to keep putting them on and taking them off. Spec for R-12 was 600-750g, which is pretty loose The resealing cans are da bomb. I think the piercing of cans is just stupid and wasteful.

Thank you again JDMMA70 for your write-up! It was most useful.

Drove it to work this morning (17 July)! Vent temperature tended to stay right around 50-52F; outside ranged 82-90F. I may add a bit more refrigerant and see if the vent temp drops a few more degrees.

Update: I added about 60g more this morning (18 July) and it appears to have dropped my vent temperatures to around 45F. You must set the control to 65 to get the system to run at maximum to measure this. Just cruising along, it appears to me the control system keeps the vent temperature around 60F. It definitely cycles the compressor, as it bumps the idle to 900rpm while the compressor is on. Guestimating losses clearing lines and such, I put in about 750g total.
 
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