New owner with ventilation problem

....also violet/black shown in the photo near the disconnect plug.

 

Yes, I can see it. Probably there was a change at some point or maybe with the 355. On my 91 348, the wire is solid violet.

 

I tested the actuator again. This time there was no smoke. The previous time I only applied power for about a second in both directions. This time I gave it a longer (feeling braver) test and let it go from stop to stop (which is half a rotation). There was no smoke this time. I think it was just that the motor had not turned for such a long time that the smoke was just a bit of surface dirt burning off perhaps? Then I inserted my multimeter set to 10A and when the actuator turned I got a reading of 0.15~0.14.

So the next step is to connect to the old wires (but I'm not holding out too much hope otherwise why would the wires have been cut at all?).

 

The actuator looks good (after it dusted off the cobwebs). I said around 0.1 A as I could not remember the exact figure I got when I was testing mine but now, when you said 0.14~0.15, I think that was what I got as well.

Before re-connecting the original cut-off wires, check their continuity when you find the other end. If broken, leave the new wires in and use them. It is possible that the chip inside the AC ECU that drives the actuator failed. There is a good thread here (do a search) showing which chip does what and how to replace them. The chips are easily available.

 

I've just connected to the original wires, and with no great surprise to me, nothing. On the plus side I found some money inside the centre console - a 10 French Franc coin! Whats next?

Also - I'm getting the vents out to de-sticky them. The right side vent popped out no trouble, but the left hand side won't budge. Do have to just apply more and more pressure till it releases or is there a knack to release the fixing clips to get it out?

 

I saw the reply from m.stojanovic after I posted. I'll have to strip the front compartment in order to find the ecu and check the wires. Back soon.

 

Right. I have the A/C ecu out and the new loom has been connected into the plug;

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I have tested the wires and all three are good and connected to the plug.

 

The 3 new wires?

Chip #6 in the ECU controls the diverter motor...

F355 HVAC ECU

Chip part number:

F355 HVAC ECU

I believe there is a company in the UK which repairs these units, but if you buy the chip for U$5 and get your local electronics store to install it, it may work out a lot cheaper.

https://ecu-stock.com/part/13799/

I can't recall if these units have a test facility which may point to the components in the system which may be faulty.

Can you see why the harness was bypassed? Chafing? Will you check the other wires going from the ECU to the actuator?

 

I will check the other 2 wires. Before I start pulling the ecu apart, is there a way I can be sure it is not the sender unit with the dials that is not the problem?

 

P.S. By the way, thanks for all the photos. I just noticed one of my wires was coloured incorrectly.

Also, can you confirm the colour of the 3rd wire from the top of the plug? From the top, there is a red (pin 14), green/black stripe (pin 15) and ??? (pin 13). The Workshop Manual says red/white stripe, but your wire looks mostly white.

 

At the moment, it could be basically anything... This is why I was hoping it was possible to interrogate the ECU.
I guess you could also check the wiring from the panel to the ECU. Do you know how to access the plug on the back of the control panel (by removing the ashtray)?

Panels have been known to fail... e.g.

https://www.ferrarichat.com/forum/threads/hvac-control-panel-circuit-board.507998/

 

The control panel is already out. I'm also doing a total "de-sticky".

 

Atta boy

 

It sounds very sensible to 'interrogate' the ecu before taking a soldering iron to it. How does one do that?

 

I may be mistaken, but I assume the SD1 tool can do this... but these are only available at Ferrari workshops. The wiring diagram does show a port for a diagnostic tool.

Perhaps Dave (Rocks) can tell us?

 

I have just checked the wires from the HVAC control box to the ecu. White, Yellow, Green, Pink, and Orange (which run to the clear plastic plug into ecu) are all good. Black is a good earth and connects with the black into the same plug. I know the Yellow+Red does not go into the ecu but into "splices" 30048. I don't know what that is, but there is a non-direct link with the Yellow+Red on pin 24 of the 'out' black plug, giving a reading of 2.4 ohm.

HOWEVER; I have a Blue/ black wire into the control box which does not connect to any of the wires into or out of the ecu. The wiring diagram does not show a Blue+Black. It shows a Green+White white which I do not have. Most curious.

Eurospare do have a couple of second-hand ECUs - just £2495 each. Not in this life...

 

A non-direct link with yellow red on the ECU? Quite possible, but the functions are not related. As the diagram shows, pin 24 is an input from the ignition lock (during start) via a splice. The splice could go to all kinds of things (including parts of the ABS system) and back to earth. The yellow red on the control panel goes to the instrument lighting dimmer, so probably goes through several lamps to earth. Are you doing these checks with the battery cut out?

I noticed another wiring colour error in my diagram. Now corrected.

F355 (5.2) HVAC Wiring Diagram

Is the blue-black wire on the same pin as the green-white wire in my diagram (I don't see any spare wires on that plug). From time to time, Ferrari owners have noted wiring colour variations between cars. I did notice a few on my '89 Spider. If it's on the same pin, it should have the same function. Does the wire look original?

Did you find out the reason for the new wires for the air distribution actuator? Is there damage to the harness somewhere? If the wiring is ok, then it's back to components. Also, as long as other panel functions are working (e.g. fan speeds), then we know power is getting to both the ECU and the control panel. My money is on a component inside the control panel or the ECU.... or the actuator is on its way out and may have fried the ECU control chip (#6).

I saw an advertisement for an ECU for U$250 (ships only to USA) from a seller with only a 66% rating. Risky.

Here's one in the UK for £514.75

https://abs-testing.com/part/13799/

Even at that price, I wouldn't be fitting it until you've given the actuator a thorough internal check (including the 3 wire feedback wiring).

 

No, but I'm only checking the wires end to end and they are not connected to anything. I'm not wanting to disconnect the battery unless I test something linked into the car so as to avoid the reset process again (as that might be part of my woes).

The diagram shows 8 wires in a row, but the connecting block is 2 rows (3 on top & 5 below). Looking at the back of the plug at the wires going in they are layed out as follows;

Blue+Black,--------------------------------Yellow+Red,-----Black
Orange,--------Pink,--------Green,------Yellow,------------White,

I have opened up the control box and visually it seems fine. There are no blown resistors, and the soldering on the other side looks OK. I can't post a photo as my photo hosting site is down.

I have checked the old cut wires and all three are good, so the reason for the new loom remains a mystery. Looking at the (old) loom wires out of the connector, starting with the gap and working clockwise I have Red+black* White + Black*, Yellow X 2, Black, Purple+Black*. The three marked * are replaced by the 'new' loom. The Yellow is good connection to pin 12. The solid black doesn't register when I connect with the chassis it seems.

Thanks for your help

 

Thanks. I'll add this detail to my diagram. Yes, the blue-black wire is the equivalent of the green-white wire in the diagram (and should get 12volts dc power with the ignition ON via the AC System fuse). Strange colour though. All of the wires coming from the AC System fuse appear to be green-white in the diagrams.

I wonder if that's the problem?
Can you check to see if there is continuity between the solid black wire and pin #4 of the ECU plug? (i.e. the grey-black wire on the loose ECU plug... not on the ECU itself). If that fails try ECU plug pin #4 to the chassis.
The diagram shows a common chassis earth for all the sensors, but check what Miro wrote earlier about sensor earths.

(EDIT: I wonder where the common sensor earth "70125" is located?)

 

It seems that the new loom is a result of somebody's crude troubleshooting method. It looks like the actuator was opened-up and re-sealed (didn't find anything wrong), then just replace/bypass some wires etc.

The Black wire must have a good ground connection, maybe this is your problem. It grounds one side of the actuator's potentiometer and, if not connected to the ground, the AC ECU will not know the position of the air direction flap and will not operate it.

 

Just remembered... The plug for the Treated Air Sensor is just forward of the air direction flap actuator. See if you get an earth on the black wire... it uses the same earth as the flap actuator.

Just make sure you're getting a proper earth on the chassis during continuity checks.

 

I have checked the pin for the black wire (post connector) and cannot find a connection with earth. I will give it a ground connection and try it, but first I must ask though, it does seem very strange that the Green wire out of the actuator turns to Black after the connector and goes to earth, and the Black wire turns into White+Black to pin 19 (not earth). Especially given than when I was bench testing the actuator I was applying 12v to the Red and Black wires and not the Red & Green. If the green out of the actuator is earth, why? and how did my bench test work?

 

I thought I'd draw how my wires differ from how they should be (for clarity) and it seems everything is as it should be, except for getting an earth connection on the Green>black wires.
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It is correct that the Green wire out of the actuator turns to Black after the connector and goes to earth. The Green wire out of the actuator is, inside the actuator, connected to one of the 3 potentiometer pins and it should go to ground (via the Black wire post connector). The Red and Black out of the actuator are the two wires to the actuator's motor. When you apply 12V to these two wires, the motor will run in one direction or in the opposite depending on the polarity of the applied voltage. When testing, you should not apply any voltage to any two of the Green, Yellow and Violet/Black coming out of the actuator as it will burn the potentiometer.

To summarise, the functions of the wires coming out of the actuator are: Red and Black - to the motor; Green, Yellow and Violet/Black - to the potentiometer. The potentiometer is, inside the actuator, rotated (like when changing the volume on an audio amplifier) by the shaft that moves the flap and the potentiometer provides signals (varying voltages) to the AC ECU which represent the position of the flap. Inside the actuator, there is no electrical connection between the Red & Black (motor) and the trio of Green, Yellow and Violet/Black (potentiometer).

 

Are the flap motors no longer available?