Ye Olde A/C shut off valve

[SVOboy]

So, this is basically what it is, I heard it from Matt first, but mehbe some feedback and stuff about developement could go up here, also, I think this should be an easy thing to study, if you ask me.

So it is basically I little thingy that measures the pressure the a/c system put on the car when the car is using it's power for moving, and then kills the a/c in hopes of not killing your gas mileage. I will poke around for some link cuz I know I have them, I just want to get this out here.

EDIT: here is the link to it on the insight forums: http://www.insightcentral.net/forum/viewtopic.php?t=3336

[Matt Timion]

I forgot all about this. I first read about this on an insight forum. The guy build it using a vacuum switch and harwiring it to the AC compressor. When the PSI of the vacuum hose was above a certain level (in other words, you are accelerating) the AC turns off. When the vacuum comes back down below the threshold, it comes back on.

I should email the guy on the insight forum and get schematics for it. It would be a very simple thing to build, and even better, very easy to install.

[SVOboy]

I think I have a link for it somewhere around here...I will post it up if I find it quickly. In any case if it is easy enough one of us could just fab it up with pictures and do a real detailed write up. If it is too hard I'd prolly talk to DieMaster as he is an electrical wiz I believe. But get yourself on AIM for a minute, I gotta show you sumpin.

[Diemaster]

<p>i'm in the process of learning asembly language. so i'll be able to do the same thing in the ecu so no wiring or hardware is nessary (unless u dont have ac :P ) just write a little subroutiene that moniters the mapsensor and controls the ac clutch. all the hardware is allready stock to do that :D </p>
<p>come to think about it the ecu allready does that. if throttle goes &gt; a particular percentage with speed and rpm signals the ecu shuts off the ac while under heavy accelleration</p>

[SVOboy]

But wouldn't it end up being a lot more work for the average not tuner person to do it the hardware way? I dunno anything about fooling with the ecu besides I don't have chip-burners or anything like that. While your idea is by far better than hardware, it might get hard unless everyone wants to drive over and visit you. Please tell me I'm wrong, I'm just starting to learn the crap from pgmfi.org so I still suck&nbsp;

[Diemaster]

<p> it might get hard unless everyone wants to drive over and visit you. Please tell me I'm wrong, I'm just starting to learn the crap from pgmfi.org so I still suck&nbsp; </p>
<p>lol i'd love the company :P no your not wrong. to the average person a simpe switch on the ac would work just the same and just as well. but in the automotive industry, were using less and less vacume. plus i dont like to splice into wires if i dont have to. i'm a neatness freak :P not only that but i could burn the chip for u a chip is like $2-3 so that would be less than the wire and switch and vacume tubing etc.. i'm not denouncing u i'm just trying to be most productive with what we allready have :)</p>

[SVOboy]

<p>&nbsp;i could burn the chip for u a chip is like $2-3 so that would be less than the wire and switch and vacume tubing etc.. i'm not denouncing u i'm just trying to be most productive with what we allready have :)</p><p></p><p>I'm not so worried about denuncification, I think though you would have to give yourself I little more out of the deal for 2-3 bucks but hell if you start burning chips you should definately talk to matt and I'd definately want one. I think I can resonably figure out the installation and all that. Mehbe if I get this free car I can part it out and afford my own burner and go learn it for kicks but for this you sound like you're already on top of it, haha. &nbsp;</p>

[SVOboy]

I figure I'll move this up so flatland can gives his opinion on how to make something like this, because I think it is definately within his scope and I'm still really interested in getting it figured out.

[Matt Timion]

I figure I'll move this up so flatland can gives his opinion on how to make something like this, because I think it is definately within his scope and I'm still really interested in getting it figured out.

Sorry I've been so busy lately, but I did talk to the guy who made one of these.

All it takes is a vacuum switch hooked up to either the A/C compressor or even the button within the cabin. The vacuum switch can be tuned to turn off/on at certain PSI. Tune it correctly (just turning a screw) and it will turn off when the throttle is open beyond a certain point.

I plan on doing this soon and making a write up, or at least soon after I make the write up for the cheap PCV catch can I'm making.

[SVOboy]

Get the hell one that, eh.

[SVOboy]

So, I'm coming close to knowing how to do this in the most clean, all electrical way. Sure, it'll be expensive (for what it is, by itself) but if it is done this way it'll almost certainly be accompanied by some other sort of modification that would be well worth the expense by itself.

What I'm talking about is modifying the ecu. Basically, the information of doing all the hardware stuff is at my fingertips, and this concept has been done before, but not on the ecu I plan to modify, so that means I'd have to figure out what the hexadecimal code looks like for this and then track it down in a large file which basically looks like nonsense, but if I can, then it'll be rather simple to kill the a/c based on load.

[Matt Timion]

This weekend my car died a few times while idling with the A/C on. When I turned the A/C off it didn't die. I now that this can be fixed in other ways, but it seems to make sense to hook up a vacuum switch to kill the A/C when the car is idling.

This could also be done with a RPM activated switch to only have the A/C turn on above certain RPMs (or have it turn OFF below a certain RPM). This way the compressor wouldn't be turned on while idling, or during other times when the compressor is the most inefficient.

I'm trying to find a non-ECU solution as to make the application more friendly to all car owners, not just Honda owners.

[Diemaster]

your ecu is suposed to raise the idle to copensate the A/C. or if the motor is rpm too low it will shut off the a/c. instead of fabing up a soultion u should fix the problem. sounds like the system is wire impropaly.

[DaX]

In Hondata you can set the conditions for AC shutoff - I'm pretty sure it's RPM dependent though instead of load [MAP] dependent.

[SVOboy]

Yeah, I plan on using crome to switch of my a/c if my ecu ever gets support by it. All the tuning programs I know of do it normally at wot, but I think you can specify the load level.

[Matt Timion]

I've been lazy with this idea lately (mainly b/c I don't use a/c) but I really want to find a cheap vacuum switch and get this figured out.

At the very least it would be a cool addition to any car. WHile I like the ECU method of doing this, not everyone owns a honda so the solution would not be universal.

I think it would be cool however to be able to sell "economy chipped" ECUs for people who want them and this would be one of the features.

[SVOboy]

I figure it I ever get off my *** to learn how to do rom switching on a single chip I'll be able to offer this as a service where there is a physical switch you can stick somewhere in the car to toggle between the performance stuff and the economy stuff. It's extremely possible, and has been done a lot, I just need to get around to it.

[DaX]

I don't know about doing it on the same ROM, but if you wire a toggle switch into the J1 jumper on an OBD-1 board, you can switch between the stock program [J1 open] and a program burned on a ROM [J1 closed].

[SVOboy]

That's true, but you can switch programs on the same rom. Some people even buy the 32 pin 1 meg roms and put for programs on there, but that gets annoying with all the wires coming off the extra pins and blah blah blah.