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Microtech microtech and a/c??

Old 07-06-06, 11:12 PM
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microtech and a/c??

well i purchased my fd and it has the microtech in it.. i went to get my ac fixed becuase it wasnt blowing cold air and found that my compressor wasnt getting the right type of signals or something like that and they did a wire job from the a/c relays to the fan relays and everything started working and blowing cold air.

so i drove the car home only to find the car wouldnt idle right it would shut off and it was starting to get really hot .

so i pulled the relay they installed and the car started functioning properly again.

so i came on here a did a search only to find that some say with the microtech the a/c system will not function properly for some reason.

whats the deal with this? .. is there a way to get the a/c to function correctly?

is this the only standalone that does this?
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Old 07-16-06, 01:56 AM
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I have the same issue, when i bought my fd the a/c would not kick in when i pushed the a/c switch. i have no idea why?, i do have hte microtech lt-8, is there a way to get it working with the microtech, or should i rewire it to a relay.
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Old 07-19-06, 07:34 PM
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bump
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Old 07-24-06, 01:02 AM
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I believe the stock ECU sends a ground signal to the AC relay which turns on the compressor. This happens when you turn on AC switch. A 12V signal comes from that switch and goes to ECU which then sends a ground to the AC relay based on certain engine parameters like TPS, boost, etc.(Someone please correct me if I'm wrong)

Well when you installed the Microtech you just eliminated all of that. I have an LTX8 and I'm using the auxiliary to switch on my cooling fans, which you're probably doing as well.

What I intend to do is to rewire my AC relay by doing this:

1. Tap into the AC switch wire (that sent 12V signal to original ECU)
2. Wire this into the 12V coil side on AC relay (this originally got 12V on ignition, so I'm cutting that original wire)
3. Ground the other side of coil
4. Use the wire in step 1. and simply tap that into the BAC wire to switch on BAC valve.
5. Ground other side of BAC valve wire.

When you switch on the AC switch (with fan on) this should send 12V to AC relay and also BAC valve. The idle will probably need to be adjusted, but will do this right from the BAC valve adjustment screw. I'll see how this works when I get another BAC valve (which I threw away when I put on block off plates) and then wire mine to work. right now I have a ghetto rig. i just use a 12V switched wire and wired that directly to the compressor.
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Old 07-24-06, 01:43 AM
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Surfpac

When you ghetto rigged the A/C. Was there any problems on the compressor, turning off to fast, due to high pressure?. Or does it seem Ok for a temp A/C feeling. I am going to do this tommorow. I already made a switch to the A/C fan. now i am going to use a relay that connects to the compressor switch and also a relay for the fan. My questiojn if you know the answer. There is 2 wires that connects to the dryer. Does that send out a signal to shut the compressor off if i direct wire that with the 12+ signal?
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Old 07-24-06, 01:02 PM
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When you press the a/c switch it sends a ground signal to the ecu via a purple wire. The ecu then send a ground signal (depending on certain parameters) to the a/c relay via a yellow/ black wire. So all you need to do is connect the purple and yellow/black wire together and you should be ok. I think they are 1E and 1L on the ecu pinout. This way the thermo-switch and the pressure switch work like factory so you dont damage your compressor.
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Old 07-24-06, 01:15 PM
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My correction, it should be 1E which is violet and not purple and 1L which is yellow/black.
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Old 07-24-06, 07:08 PM
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wow

Originally Posted by jiggaFlexxx
When you press the a/c switch it sends a ground signal to the ecu via a purple wire. The ecu then send a ground signal (depending on certain parameters) to the a/c relay via a yellow/ black wire. So all you need to do is connect the purple and yellow/black wire together and you should be ok. I think they are 1E and 1L on the ecu pinout. This way the thermo-switch and the pressure switch work like factory so you dont damage your compressor.

Thats all i have to do? Seems so easy.. Do i need to do anything else, like have a 12+lead that connects to the yellow/black or what about a 12+ lead that goes to the violet?. What gives the logitic control power if a hook it the way you said?. Also the wire that comes out of the compressor "clutch" is that a negative lead or positve?. I want to know because, i am going to turn one of the auxilary ON, on the MT ecu..
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Old 07-24-06, 08:36 PM
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The a/c button in the car when depressed sends a negative signal to the ecu via the voilet wire......The a/c relay at the front of the car is triggered by a negative signal via yellow/black wire from the ecu...... The a/c relay when triggered then sends a positive 12v signal to the compressor via a black/red wire...So basically all you have to do is connect the y/b and the violet wire and you are good to go.
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Old 07-24-06, 11:02 PM
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Wow, thanks for clearing that up Jigga. What about the BAC valve to control idle when the AC comes on? How do you handle that, with the Microtech?
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Old 07-25-06, 04:05 PM
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Hey Surfpac i also live in Pembroke Pines but i'm currently spending my summer in Jamaica....

I have the LT-10s, i dont know if the wiring for the ltx8 is the same.
I tap the microtech (aux input#1) blue/red wire directly on the wire that connects to the compressor black/red wire so that whenever the compressor turns on by receiving 12v it also triggers the BAC controls in the microtech.
The BAC valve has two wires coming from it. You need to connect one of these wires to a ignition switched 12 volt source. The other wire should be connected to the white/black (aux output#3) wire that comes from the microtech. This white/black wire sends a variable negative signal from the microtech to the BAC valve to determine how much air to bypass whenever (aux input#1) blue/red wire receives a 12v signal......Follow....I hope i'm not confusing you.
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Old 07-25-06, 04:18 PM
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BAC valve now connected you go to Screen 29: Auxillary Output/Input Functions. With the engine running and a/c on you can adjust the rpm by changing the value of InpAIRadd. This increases the idle by opening up the BAC thus adding more air. The higher the number the wider the BAC valve is opened. If necessary you might also want to adjust the InpEnrich. This adds more fuel to compensate for the additional air added by InpAIRadd function. All these adjustments only comes into effect when the a/c is activated.
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Old 07-26-06, 02:57 AM
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This is very informative, i got my microtech with my car its LT-8, where can i get the cable and software from, or even a hand controlller


and to stay on topic what if i just wired y/b and the violet wire without touching the idle and such.
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Old 07-26-06, 12:45 PM
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[QUOTE=FD3S-K]This is very informative, i got my microtech with my car its LT-8, where can i get the cable and software from, or even a hand controlller


and to stay on topic what if i just wired y/b and the violet wire without touching the idle and such.[/QUOTE}


I bought mine from www.microtech-efi.com.
Its norm for the idle to drop 2 to 300 rpm when the a/c is activated. So depending on your current idle setting you might have the engine stall when the a/c is on.
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