Aircon electronics

IZU069
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Post by IZU069 »

The 12mV sounds like noise....

When are you getting 12mV - with the ignition on? (That's normal - the relay will be off.)

And what sort of relay did you buy? You need an SPDT & SPST (ie, just get 2x SPDT) to substitute for the grey relay.
Those grey relays are reasonably common in Jackaroos & Rodeos (1980-1990) as well as other Jap vehicles, though like the brown, there is usually on one per vehicle. (Black SPDT & (blue) SPST are common.)


I'd hold off on the auto-elec for now - especially if the above is NOT what you expected....


All you are likely to have fried is fuses.

The wire flinks can be changed to ordinary blade fuses (at least capacity-wise; I haven't checked discrimination aka coordination or whatever the heck they call "sequenced fusing").
My preference is to use a battery terminal mounted 3-flink box of a Hyundai (I think), though Toyota have similar - all be it with a bolt-in main fuse.
The Hyundai (or Daiwoo?) has all 3 flinks as plug-ins, and the centre flink can be connected to the battery or independent - it uses a flying spade wire. Mine is configured to sit between the alternator and headlights.

I did start to check the wire gauges ages ago, but dropped it thru lack of interest.


But you will need to trace thru the wiring with a test light else multimeter.
Not that I use test lights, but they should be used so overcome the high-impedance of meters etc. (And complications like 12mV which - compared to 12V - is zero, zilch, nothing, non-existent.)

Hence learn to read the wiring diagrams, and understand what is connected or active/energised when....


A question for you - when does (should) that relay come on - ie, receive 12V and be energised?
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vinnie55
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Post by vinnie55 »

The relay should come on when the ignition is in the on position.
that way when you are cranking it turns off.
then when the engine starts and your drop back to on it should then work.

but yeah. totally seeing a pro. I've got an uncle who is a mechanic i'll give him a call. see if he can recommend an auto electrician or something.
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Post by IZU069 »

vinnie55 wrote:The relay should come on when the ignition is in the on position
WRONG! (Unless I am!)

The grey relay comes on when you are cranking.

Check the wiring diagram.

Hence why you have your problem....
Again - unless I am wrong. But those air-con cutout circuits are not required to be of fail-safe design - eg - like some sensors that are normally closed and open when "active" - eg, proper oil-pressure circuits; KE Laser fan circuits and my 90-degree "normally closed" klixon fan switch. [Yes - I've run electric fans since 1978 and NEVER had them automated until ~2 moths ago!]
Anyhow, cut the wire to the NC switch and the fan (or oil-light) comes on. And if the "inverting" relay fails, it should fail in the closed position, hence also turning fan or oil-light on.
The grey relay when de-energised connects the aircon thru it's NC contact. Cranking energised the relay hence opening that aircon circuit and turning off the clutch or whatever it "turns off".

Hence you need an SPDT relay for the aircon (NC contacts), and another set of NO contacts for the "other" circuit (ie, a second SPST or SPDT relay). The relay coils are paralleled so they both energise during cranking.
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vinnie55
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Post by vinnie55 »

Not the grey relay, the relay I ran myself
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Post by vinnie55 »

But if it activated when cranking, then the AC would only be on when cranking.....
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Post by IZU069 »

No - the aircon is normally on - it is connected to the NC (Normally Closed (when de-energised)) contacts of the relay.

When the relay (coil) is energised by the +12V cranking/starter signal, the relay energises thereby opening the aircon circuit and turning the aircon off.
Meanwhile the other 2 NO = Normally Open contacts close (and I think that powers the starter solenoid or starter relay).


Check the Starting diagram.


In summary, the aircon is ON when NOT cranking.
The relay is energised (on?) when cranking, hence the aircon is OFF.


Easy eh?

So, what relay did you use to replace the grey relay?
If you used ordinary relays, you must be using TWO relays of which one MUST BE a changeover type (SPDT).
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Post by vinnie55 »

OK. SO.
I proceeded with my wiering job with a relay I bought. sent 12V to the white and red wire on the fuesebox (AC fuse).

AND

guess what.

it fired up.

Got AC. for a few seconds it was ALL working. Thurmo fan under bonnet. AC controll pannel.

awesome.

so I started fiddeling with it. see if i could get some cold air coming through....

and then....

SMOKE!!!!

turned it off. unwired my setup.

It appears I cooked the black AC relay in the front of the car, that little box just behind the front right headlight.



next step.
Auto electrician.

I'm done blowing shit up.
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Post by IZU069 »

Yep - that's what we call a short circuit - it releases the smoke held within wires.

You connected +12V to the battery -ve (earth, chassis, ground).

How?

See the 3rd diagram "Cooling Fan and Air Conditioner 12-88 Electricals" from earlier...
You connected +12V to the top right WR wire.
Hence supplying +12V to the AirCon & BlowerMotor etc.
See also how that WR goes leftwards through connector B4 and becomes the bLue into "RELAY: charge & aircon"?
Well that black (changeover) relay connects the bLue hence W/R circuit to 0V chassis if it is NOT energised.

You may have burnt out the relay which is an easy swap, though I recon you have probably burnt out the blue wire or the black wire (to chassis) underneath the relay's cradle. They will have to be traced to ensure they haven't melted other insulation....


Maybe I should have stated to NEVER supply power to a circuit unless you are sure you have it isolated etc.
Though I did say:
IZU069 wrote:But you will need to trace thru the wiring with a test light else multimeter...
And I was asking how you imitated the dual-pole "inverted" switching of the original grey relay, & interpreted its operation.


If you are in too much of a hurry, then yes - take it to a good auto-elec. It may cost you heaps, but it may save you heaps more.
And I suggest avoiding mechanics. My mate's mechanic took weeks (changing fuel pumps & crap) and finally blew the EFI's ECU when the problem was MERELY bad contacts on the flinks! (And it was the owner/mate that found it - something I had predicted and warned of a few months earlier FIGJAM LOL!)
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Post by vinnie55 »

Yeah. I mean i'll probably run it past my mechanic, who is my uncle and very skilled and trusted, but I will get him to recommend a good auto electrician and show them that "Cooling fan & air conditioner" wiering diagram.

all that said I have learned much from this excercise.
I now know roughly where the white wire with red runs. It goes to that relay that I melted the plastic on.
There is also a wire by the same descrpition entering the fuse of the blower fan in the passenger footwell.

I also learned, that that weird little compartment that opens under the glove box is infact a passenger KNEE air vent. WTF! they thought of EVERYTHING.

Also found I am missing a vent under the steering wheel which does much the same.
Might start hunting for one...

All that said, I now understand a little more of that wiering diagram. so I will trace the course of that wire that leads into the circuit. (the one that goes from the battery and around the outside of the diagram to the fusebox where I ran the voltage to.... oops.)
I will trace it but I wont fuck with it.
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Post by IZU069 »

vinnie55 wrote:...that weird little compartment that opens under the glove box is infact a passenger KNEE air vent. WTF! they thought of EVERYTHING. Also found I am missing a vent under the steering wheel which does much the same.
It's a crutch vent.

Most Jap cars have them. They are often removed on Australian models (we use soap).
It probably shows how little GMH had to do with our Piazzas! (LOL!)
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Post by vinnie55 »

I hell want a crutch vent.
The main thing every car that's not a lexus or mercedies lacks is air conditioned seats.
It's always your back that gets sweaty in a car on a hot day.
I recon a crutch vent may help guide air into those regions.
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Post by IZU069 »

Update on aircon relay etc.

It seems its coil is actuated by the charge light circuit (the "L" circuit from the alternator; low/earth when not charging, +12V when charging).

That's FYI - it can be difficult tracing where the control/coil leads for the RELAY charge & air-con come from. But according to the Power Source No1 fig, the +12V comes from the WG White-Green alternator "L" terminal, and the coil is NORMALLY earthed by BG Black-Green through the Starter Relay (and broken during cranking).


In other words, it is essentially like typical FPR (fuel pump relay) or fuel enable (fuel cut) solenoids - they are enabled when the alternator is charging - ie, when the engine is running, though the Piazza cuts the air-con during cranking (whereas fuel pumps & fuel-cut solenoids are not).

[ The FPR is like the UIBI - the Ultimate Intelligence Battery Isolator) - the name assigned by foreigners to the charge-light activated battery isolator (relay) being superior to those expensive "smart" isolators. I should refer to the UIFPR - Ultimate Intelligence Fuel-Pump Relay - but that might offend the 160-odd morons on another forum that claim to be dumber than an allegedly high dope-smoking poster LOL!
Geez, sometimes I just can't resist. Or am I merely relaying? ]
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Post by wedgenut »

I hell want a crutch vent.
Ah well it is really lucky that the Piazza has a crutch vent then. Course you need to make sure it is open by sliding the control and directing the vent up yer kilt. If you want the best blast you probably need to close off any other vents not needed because while it exists it isn't that strong an air flow except on full fan setting.
So many cars, so little cash
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Post by IZU069 »

Lacks the superior firewall vent of the Wasp, Florian, and Bellel (not Bellett) - but ball aren't what they used to be.
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Post by vinnie55 »

OK! So it has been a shamefully long time since I have commented on this thread.
....Because it took a shamefully long time for me to get it fixed.

BUT!

I have a mate from work who is an auto electrician, he's a busy man but eventually he turned up to work one night with his tools on him and 5 minutes later the problem was solved.

That 5 pin black relay that I melted the fuck out of. he just put a headlight one in it's place and the AC fired up.
Just like that. I now owe him a slab of beer.

To fix the job properly I will pop out the little connections and put new crimps on them, and the one that is covered in melted plastic I will cut from below and run a new wire and crimp.

I HAVE AIR-CON AGAIN! I CAN DE-MIST MY WINDSCREEN! WOOOOOOO!!!
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