New Idea for S14 RB20 AC Solution

[josephrm]

Good afternoon guys. So I've been trying to figure out what to do about air conditioning. Im swapping an RB20DET into my S14. I haven't read of anyone doing it, but I would like to keep the compressor from my KA. It is of a newer and more efficient design than the one that came on my RB. We don;t need to get into specifics about the compressor, just let it suffice to say that I would like to keep it.

The brackets are quite similar in the manner in which they attach to the block. It looks as though the KA bracket will bolt to the RB block. The only problem that I am seeing is that the pulley would then be inline with the same part of the pulley that runs the alternator and water pump. Can anyone think of a reason that this would be a bad thing to do? If I'm not lazy, I will attempt to fit it and take pictures tomrrow.

If I were able to work this out, there would be no modification necessary to the AC system, and the system would not have to be recharged!

On a side note, is there any safe way for me to discharge the AC system myself? Without any special tools, I mean.

[240z4u]

Thats been discussed, and was what I wanted to do. I think a guy drilled a flat plate to move the mounting points out further so the belt lined up.

No good way to discharge it, if it worked when you took apart dont open it. If you leave the drier exposed to open air it will not work anymore.

Good luck, and let us know what your gonna do.

BTW, you considered different options for wiring? The stock KA computer controls the compressor.

Evan

[Carl H]

bolt an rb25 ac compressor and bracket to the 20, it should bolt up...not sure about ps pump clearance tho.

[josephrm]

Hmmm. I would try it, though I don't have an RB25DET compressor and bracket.

Let's assume for a second that the pulley aligns with the first section of the crank pulley, the one that runs the water pump and alternator. Can anyone see a reason why this would be a bad idea? I do know that it would decrease the contact area between that belt and the crank pulley, thereby decreasing the amount of force the crank can exert on the belt to turn the accesories(and in this case, thats 4 different pulleys). In fact, I'm not sure if Ive ever seen a belt that long...

240z4u...

That's interesting. By no means do I have first hadn experience with this, but from what I have read, the ECU in no way controls the compressor(aside from telling to shut off under WOT, etc.), which I imagine the RB ECU will do as well.

[Carl H]

the car contols the ac plain and simple.all the ecu does is give the go/nogo signal for the ac to kick on.the rest are saftey devices...just fill to the proper pressure and you'll be fine.

[josephrm]

Thanks, Carl. Anyone know anything about belts needing enough contact with a pulley to be driven correctly?

[josephrm]

Well, thats a moot point. The bracket bolt holes are a few millimetres off from the ones on the block. However, this is a good thing. Now i just have to take super accurate measurements. and get a couple of brackets made. yay!

[240z4u]

Are you using the stock KA compressor to make it work?

If your having a bracket made and it works, I would like to get measurements. Or maybe your machinist could make me one too?

Thanks buddy - Evan

I agree with carl btw, just wanted to make sure you had considered wiring.

[josephrm]

Actually, Carl has been kind enough to do my wiring for me. Im going to the machine shop today, if what they give me works out, ill post the dimensions on here.

btw, yes stock S14 KA compressor

[uber95]

You back from the machine shop yet????

[josephrm]

lol, yeah. it would have cost me about $250 for them to do the design work, so I took some good measurements and I am preparing some plans in AutoCad for them. I'll take the plans to them on Monday, and sometime Monday evening I should know if it works.

[josephrm]

okay, parts will be ready tomorrow morning and I will let you all know how it works.

[uber95]

okay, parts will be ready tomorrow morning and I will let you all know how it works.

Are ya back yet?????? August in the dirty south is a hawt mawtha fawk'r You must post pics or be

[josephrm]

Okay, I need to go find a picture hosting service, but here's the lowdown:

Bottom two bolt holes were maybe 1mm off, but I got it to bolt up so, no problems there.

The big problem is that I must have erred in my measurements somewhere in regards to the fore aft placement. The difference between the RB and KA brackets was 29mm as I measured it. However, my pulley is now 3mm or so too far forward. These things cost me $126 at my machine shop, so I am not going to get another set made. I'm going to just slot the holes for where my brackets bolt to the block and I should be good. Then I will post updated dimensions for my brackets.

[josephrm]

they turned out well for something that I designed...too bad I didn't get it spot on the first time...

[lazyboi444]

So they line up correctly with the crank? If so i would love to know the dimensions lol.

[josephrm]

no, right now the pulley is 2-3mm to far forward. I'm going to correct it and then I will post dimensions......it'll be a few days. Good news is that it does all bolt up properly.

[Sky80]

Wow props to you, this is the most action ive seen towards making the AC work with the RB... Keep up the good work, and dont give up like everyone else!

[madcowvert]

your still going to need to extend the lines right? the 240sx line won't reach atleast the one from the firewall shouldn't.

[300Plus]

... I thought I posted this but I guess not... WHY?? You paid more for the bracket to be made then it would have been for custom AC lines ?? I paid right at $100 for my 240sx lines to be extended, have the rb lines added and a new drier (like in my thread) zer...67002 )

I mean you still have to do the same wiring as you do if you were going to use the RB compressor...

[240z4u]

Personally, I prefer using the KA pump for one reason.

Availability. And I don't know if my RB pump is good or not.

Its great that we may soon have two options! Thanks for your effort and research guys!

Evan

[josephrm]

yeah, I was thinking about the cost vs. custom lines today......oh well, it was mostly out of curiosity's sake. I rarely use it anyway.

[khafra]

How different is this from the S13? I'm new to Nissans, but I'd kinda like to add A/C to the RB20DET S13 I just bought, even though the previous owner didn't think it was important here in FL. If the corrected CAD models and/or measurements for the brackets are available, could you share those?

[josephrm]

from what i understand, the brackets I have designed would not work. Aside from the advice others have given, it looks like my bracket deal is a complete no go. It mounts the rather large S14 KA AC compressor to far out and interferes with the tension rod brackets. or the frame rail. Either way, it won't work. I'm just going to keep all of my AC components and RB compressor and get custom lines made if I decide I want AC. I haven't been using the AC for the past two years anyway.