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Need some advice on ac wiring R33

nicostar

By nicostar,
in Car Audio & Electrical

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GTSBoy Grand Master

GTSBoy

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Well, you could try poking 12V into ECU pin 46 and see if you get 12V out pin 9. It should also idle up when you do that. If all that works then look to the signal that should be coming from the AC controller. If it doesn't work, then ponder whether you've got pin 9 even hooked up! And so on.

If the ECU is broken in some way (not the wiring), you could probably trigger the AC relay direct out of the AC controller, but then you won't get idle up.

nicostar Explorer

nicostar

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2 minutes ago, GTSBoy said:

Well, you could try poking 12V into ECU pin 46 and see if you get 12V out pin 9. It should also idle up when you do that. If all that works then look to the signal that should be coming from the AC controller. If it doesn't work, then ponder whether you've got pin 9 even hooked up! And so on.

If the ECU is broken in some way (not the wiring), you could probably trigger the AC relay direct out of the AC controller, but then you won't get idle up.

the thing is, I have probed every single wire from the HVAC unit whilst turning ac on and off, and I see no change in any single wire from volts to ground. The ac button lights up and light goes away when it is being switched and it shows "ac on" on the display and goes away when it should be off.

Will try that test on the ecu however.

 

Edited by nicostar
GTSBoy Grand Master

GTSBoy

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Well......that's a whole 'nother story. Because the AC controller doesn't necessarily just throw the compressor on as soon as you power it up, or even press the A/C switch. You have to have the upstream conditions satisfied. Things like the refrigerant pressure switch and so on.

If you've got borked wiring in other parts of your conversion then all bets are off. You can jumper shit out until it runs and then see what it took to make it happen.

Oh, and in my previous post, where I said "chuck 12V into", I would probe first with a multimeter and see if there is power there already, because if there is then you should supply an earth at that point to make things happen.

nicostar Explorer

nicostar

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28 minutes ago, GTSBoy said:

Well......that's a whole 'nother story. Because the AC controller doesn't necessarily just throw the compressor on as soon as you power it up, or even press the A/C switch. You have to have the upstream conditions satisfied. Things like the refrigerant pressure switch and so on.

If you've got borked wiring in other parts of your conversion then all bets are off. You can jumper shit out until it runs and then see what it took to make it happen.

Oh, and in my previous post, where I said "chuck 12V into", I would probe first with a multimeter and see if there is power there already, because if there is then you should supply an earth at that point to make things happen.

ok will check for power from pin 46 and test, pressure appears good and refrigerant is in the system, I don't think the compressor relay would turn on the compressor when given the ground signal from inside cabin if the pressure switch wasn't working, the ac wiring from the hvac unit are intact, only wires chopped were the ones that went to ecu from body loom connector to ecu.  

apart from the pressure switch can you suggest what else needs to be working? the only sensor not working at the moment is the outside air temperature sensor according to the hvac self diagnosis.

nicostar Explorer

nicostar

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16 hours ago, GTSBoy said:

Dunno, but seems likely.

well HVAC unit showing code 20 currently which means all sensors ok, ac wires hooked up how they should be through the ecu and nada ac works. still the grey wire for "pin 36" is the only one left out. Also the engine doesn't seem to idle up when power steering pressure is present (locking the steering wheel all the way this switch is hooked up to send signal to pin 19 so no issues with wiring switch is also working) nor when pin 46 is grounded, 12v is present in pin 46. I've read somewhere that a bad o2 sensor can cause idle to not respond unless you plug it out or replace it, any advice would be good, I am hoping that is the reason why ecu won't idle up when ground signal sent to pin 46.

GTSBoy Grand Master

GTSBoy

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In the RB20DET engine loom the O2 sensor wiring runs with the PS switch wiring. I had the O2 sensor cause the wire to burn, which damaged the PS wire which left me with heavy steering. They are not related electrically in any way except for the fact that they run side by side.

nicostar Explorer

nicostar

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11 hours ago, GTSBoy said:

In the RB20DET engine loom the O2 sensor wiring runs with the PS switch wiring. I had the O2 sensor cause the wire to burn, which damaged the PS wire which left me with heavy steering. They are not related electrically in any way except for the fact that they run side by side.

can you explain run side by side? which wire goes into which? o2 sensor has 3 wires (power, signal and ground) the ps switch has 2 (one side grounded and the other continues the ground when switch is closed)

nicostar Explorer

nicostar

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On 7/25/2019 at 8:55 PM, GTSBoy said:

In the RB20DET engine loom the O2 sensor wiring runs with the PS switch wiring. I had the O2 sensor cause the wire to burn, which damaged the PS wire which left me with heavy steering. They are not related electrically in any way except for the fact that they run side by side.

oh ok, well in that case the wiring for the both are fine for me, would you happen to know if the ac control unit has a ac switching signal that you can see a change with a volt meter or test light when ac button is pressed on and off?

Also if I put a ground to pin 46 shouldn't pin 9 send out a ground to the compressor?

GTSBoy Grand Master

GTSBoy

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4 hours ago, nicostar said:

would you happen to know if the ac control unit has a ac switching signal that you can see a change with a volt meter or test light when ac button is pressed on and off?

I have an R32, so I have an R32 AC control unit, which we can see from the wiring diagrams above does things a little differently to the R33 one.

4 hours ago, nicostar said:

Also if I put a ground to pin 46 shouldn't pin 9 send out a ground to the compressor?

I have an R34 ECU, so the pins are all different to both of the above. And, getting the AC to work after the engine transplant was a major exercise. We had to do some things with relays and other tricks with the pressure switch. So my car is not able to serve as an example that I can measure stuff off for you.

Further to that, You should put a multi-meter onto the terminals in question and determine if they have 12V or ground on them, before trying to put any 12v or ground of your own onto them. If you put raw 12v onto a terminal which is continuous to ground, you are making a high current short circuit and can fry shit. Similarly, if you simply ground a pin with 12V on it, you can be making a short that will burn shit up. You can also use a test light to see what's what on those terminals. Close examination of the wiring diagrams can also inform you of which way the ECU terminals are most likely to work. They USUALLY act as the earth end of a switching circuit. But some do not (like some of the fuel pump outputs.)

nicostar Explorer

nicostar

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On 7/25/2019 at 12:27 AM, GTSBoy said:

Oh, and in my previous post, where I said "chuck 12V into", I would probe first with a multimeter and see if there is power there already, because if there is then you should supply an earth at that point to make things happen.

 

On 7/25/2019 at 12:20 AM, GTSBoy said:

Well, you could try poking 12V into ECU pin 46 and see if you get 12V out pin 9. It should also idle up when you do that. If all that works then look to the signal that should be coming from the AC controller. If it doesn't work, then ponder whether you've got pin 9 even hooked up! And so on.

If the ECU is broken in some way (not the wiring), you could probably trigger the AC relay direct out of the AC controller, but then you won't get idle up.

1 hour ago, GTSBoy said:

 

Further to that, You should put a multi-meter onto the terminals in question and determine if they have 12V or ground on them, before trying to put any 12v or ground of your own onto them. If you put raw 12v onto a terminal which is continuous to ground, you are making a high current short circuit and can fry shit. Similarly, if you simply ground a pin with 12V on it, you can be making a short that will burn shit up. You can also use a test light to see what's what on those terminals. Close examination of the wiring diagrams can also inform you of which way the ECU terminals are most likely to work. They USUALLY act as the earth end of a switching circuit. But some do not (like some of the fuel pump outputs.)

 

unless earth doesn't mean ground anymore, I am fully aware of what happens when + meets -
I do have an idea how the ac should work
I currently can't get it to work and just need some advice. At this point I am unsure I will find that advice here. Thanks for trying to help all the same mate.

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