Hey Steve, I emailed you back but am also going to post on here to help others out with this situation as well. I'll word it differently for the forum too
In regard to running Air Conditioning on the SR20, you have (really) two options...one is to find someone who can make lines for your setup (few and far between, and expensive) or to run one of my adapter brackets and retain the DOHC KA lines/compressors/wiring, so it works like stock and fits like OEM. This is great for 90% of owners out there, however it does leave the SOHC guys without true support.
The main reason behind this, is that the SOHC cars utilize a different tensioning system (in regard to the belt) than the DOHC cars (which use the OEM bracket with a tensioner pulley vs the SOHC which uses the actual compressor). Because of this major difference, rendering a conversion bracket for the SOHC to SR20 makes it very cost prohibitive, and that simple expensive buy in is often above the costs most are willing to pay. Atop of that, we're now 'hoping' that the old compressor still works...and atop of that you're also at the mercy of a limited part supply in regard to used compressors
However all is not lost for SOHC cars as the solution to the issue is actually quite simple, and MUCH cheaper/easier than most think. Being that I've never had a SOHC setup to test or work out, I've forever been at the mercy of forum folklore, and it was refreshing when Dave Lee came though and sent me a awesome email (as well as keeping me updated) in regard to how he sorted it out.
Below is Dave's email:
Hi Cody,
If you have any specific questions or concerns about the SOHC install, I can answer them. I hate rewriting what is already out there- for example repeating the FRS wiring guide on which wire goes to the ECU.
The reason I did things the way I did, was because there was no way a service technician was going to be able to correlate the 180SX, and two versions of the 240SX "if" things didn't work. I can hear it now, "you have a bad condensor fan," or something along those lines. Heck, I worked aviation electroncis for over 20 years, then electronics for another five years.
And how in the heck does one get custom lines made? One of the lines that "should" be built is the high side coming from compressor to condenser. On the SOHC, the condenser is in front of the radiator, but behind the front mount intercooler. (FMIC) The front bumper and FMIC have to be removed to even get to that line. So does one take the car to a shop, then have the technican remove all that stuff? Not on our car. No way. Can't drive it with that stuff removed, so the only option would have been to tow it to a shop to have the line made, or buy the tools and make it myself. I chose a third option, which was modifying the line. The low side line goes from the compressor, behind the engine, to the firewall connection. That line can more easily be made with the car in an operational condition.
To modify both of these lines, I cut off the extra mounting hole and flange from the lines. SOHC compressor has two mounting bolts per line, DOHC has one. But the lines WILL fit without having the flanges cut, but there is little room to deal with that extra metal down there. I spent a long time getting the lines to seal, but with a large box of o rings, and using my lips (no jokes please)
I was able to get it to seal finally.
The SOHC compressor plug does not fit the DOHC compressor. In my case, I solder spliced the SOHC receptical to the DOHC compressor. I used heat shrink tubing on it. That allowed the stock SOHC plug to fit. I could have done a million different things to make that work, it's only one wire after all.
I purchased a new OEM SOHC receiver/dryer. SOHC because I was using SOHC lines and didn't want fitment issues there too. One of the few parts I could find. I went through two condensor fans before getting one to work. However an inexpensive electric 12" fan would have worked just fine. On the original SOHC configuration, the condensor fan is controlled by a thermoswitch located in the lower radiator hose. (KA) Obviously, the SR20 doesn't have this, so there needs to be a way in which to have the fan turn off and on based on temperature. In my case, I already installed a temperature switch at the top of the head in a special housing for the radiator electric fan
system we installed. I "could" use that, but I worry about running too much current through it. So the answer for that would be to install a second relay to operate the condensor fan, just like the radiator fans are configured.
Or, I could get an additional temperature switch and special hose and use that without a relay. What I have so far, is the condensor fan jumped, (shorted) so that any time the AC is turned on, the fan turns on. It's very hot here, (97 today) so for around town, that works. But on the highway, I would worry about the airstream loading the
condensor fan and burning it out. So eventually this needs to be controlled via temperature.
Everything else I did is pretty much out there...ECU pinouts were spot on, except that everywhere mentions pin 10 as being for AC. It isn't listed as doing anything on the 180 schematic, and it isn't doing anything on our car. Just pin 106 from the AC relay which supplies a ground for the relay, and 41 to the control box from plug F3 located
above the passenger kick panel.
Thanks again for the brackets Cody, they have worked fantastic!
Hopefully that information works for you, as well as the rest of NICO in regard to this issue. SOHC bracket questions has got to be the number one email/PM I get, and forever I've always had to suggest converting the entire setup over to DOHC. Now with this information it is MUCH easier.
So with that all considered, the parts you will need to make it work are:
1. SR Tensioning Bracket (either Redtop or Blacktop bracket will work, as both bolt to the block the same)
2. DOHC KA compressor (either S13 or S14 compressor, so long as it's DOHC, will work as the brackets interchange)
3. (and most important) a codyace /
http://www.SR20AcBrackets.com conversion kit.
Now before anyone thinks 'oh man, I don't know what bracket or compressor I have', you can easily goto my website (
http://www.sr20acbrackets.com) and compare the parts you have with my guide, and purchsae them directly. Even if you have an S14, with a Redtop Bracket, you can use a S13 compressor and a bolt it to your Blacktop...just compare the parts you have to my guide and purchase them as is.
As in my Fabricators marketplace post here, if anyone has any questions please feel free to PM or email (codyace AT gmail DOT com) at anytime!
Whew...a mouthfull I know. But it's information that needs to be concrete. Hope I can help someone out!
http://www.sr20acbrackets.com
