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View Full Version : Possible Addition to "Make A/C Work With Swap" Thread in Tech Archives



joe's gt
07-27-2009, 12:57 AM
For anybody whose A/C doesn't work after a 3s swap and wants to solve the problem with a manual switch, the compressor must cycle so you must remember to turn it on and off. I have burnt up 2 compressors forgetting to do this.

This is something I did a while ago, but thought it would be a good addition to the thread in Technical Archives.

Hook any sort of cyclic timer like this (http://www.hobbytron.com/UK191.html) in line between the switch and the compressor which would automatically cycle the compressor.

The supply voltage is 9V, so you'd have to use some type of device to step down the voltage like I did, or you might be able to find a circuit similar to the above timer that would allow for a greater supply voltage.

Lagos
07-27-2009, 07:56 AM
isn't it a lot easier to just rewire the ac to work with the stock ac amp. its about 3-5wires total that make the system work.
I have working AC on my 6th gen car, so it should be even easier to do in a 5th gen.

If you really want to use that thing, you would want to use it to trigger a relay, and not step the voltage down or anything like that. the 9v would be enough to trigger the relay, and then you can send a fused 12v from the battery.

But it really isnt that hard to get AC working with the factory wiring.

Smaay
07-27-2009, 02:43 PM
well since we are on the subject. how about an explanation for this?

joe's gt
07-27-2009, 07:42 PM
Weren't there like 4 different A/C systems for the 5th gen? Idk, I tried wiring it up, and the a/c didn't work. There was one A/C input on my 5s ecu that wasn't even present on my jdm 3s ecu. I wired up the compressor and the other 2 or 3 that matched the jdm ecu and it still didn't work.

And how does a trigger relay cycle the compressor?

This timer already uses a relay.

You just need 9V to trigger the timer, hell, maybe even 12 would work, idk in depth about how much the circuit can handle.

But all you need is 9V to trigger the timer, and a separate 12V source is attached to the "COM" and "NO" ports and the relay opens and closes the circuit for the time intervals you define.

The 12V source attaches to the "COM" port and then you run a wire from the "NO" port out to the compressor.

Lagos
07-28-2009, 05:22 AM
Weren't there like 4 different A/C systems for the 5th gen? Idk, I tried wiring it up, and the a/c didn't work. There was one A/C input on my 5s ecu that wasn't even present on my jdm 3s ecu. I wired up the compressor and the other 2 or 3 that matched the jdm ecu and it still didn't work.

And how does a trigger relay cycle the compressor?

This timer already uses a relay.

You just need 9V to trigger the timer, hell, maybe even 12 would work, idk in depth about how much the circuit can handle.

But all you need is 9V to trigger the timer, and a separate 12V source is attached to the "COM" and "NO" ports and the relay opens and closes the circuit for the time intervals you define.

The 12V source attaches to the "COM" port and then you run a wire from the "NO" port out to the compressor.

I see what you mean. So the unit you bought already has its own relay.

Lagos
07-28-2009, 05:26 AM
well since we are on the subject. how about an explanation for this?


You might want to take a look at this thread I posted up on 6gc a while back. Pretty much tells you everything that needs to be done to make it work.
http://www.6gc.net/forums/index.php?showtopic=39327

The only thing you have to custom rig up is the ac idle up valve.

joe's gt
07-28-2009, 07:48 AM
The only thing you have to custom rig up is the ac idle up valve.

lol. yeah, I have yet to do that. I just end up raising the idle during summer time. I have to go to the junker and look at how its rigged up. Maybe I can make a custom bracket or something.

Lagos
07-28-2009, 08:15 AM
You need two things to make idle up work.
The mechanical valve, and an electronic vsv.
After that, its just a matter of wiring up the vsv to any 12v source that gets power when you press the ac switch, and the other end to a ground.
Ive had mine setup for a while now. Works great.

ChrisD
07-28-2009, 05:27 PM
Another thing I need to get done...but I need a recharge first. Any idea how long you should cycle it for?

joe's gt
07-29-2009, 02:44 AM
haha. not really. I did 3 minutes on 1 minute off, so about a 75% duty cycle. Mine ain't workin right now cuz I got a leak. I really need to replace the expansion valve and receiver/drier, but don't got the money right now. I didn't know there were o-rings near the expansion valve when I did the r134a swap, so I think that's where my leak is.

When my a/c wasn't leaking tho, that duty cycle worked w/out problems for 2 yrs.

Lagos
07-29-2009, 10:06 PM
so just to recap.. how exactly do you have this wired in again? You manually set up an after market switch, to send 12v to just the ac clutch and have your timer wired in between and thats it?

joe's gt
07-30-2009, 06:35 AM
Positive wire to one side of switch, other side goes to power (positive terminal) on cyclical timer. Negative terminal of cyclical timer goes to ground of course.

Then on a separate circuit, positive power wire to "COM" port and another wire connected to the "NO" port runs out to the compressor.

So essentially two separate circuits. 1 for power to the timer, and 1 for power to the compressor that runs through the relay.

When I flip the switch, the cyclical timer is activated, which opens and closes the relay per whatever duration you set, which controls the power to the compressor effectively cycling it on and off.

There may be other adjustable cyclical timers or an easier way of doing it, this is just what I did.

Not saying its the easiest way, just a way to prevent your compressor from burning up from an oblivious operator such as myself.

Hey Lagos, how did you mount your a/c idle up vsv? Did you make a custom bracket? I looked at the throttle control bracket and am having a hard time figuring out how to rig up the idle up vsv.