New owner with ventilation problem

Andrew, were the potentiometer's resistive surface and wiper arm/s visible when you dismantled the actuator? Did you try cleaning the contacts?

 

I'm lost here. Thread too long. Was it established that the ECU and things like the outside air temp sensor are OK?

 

The excessive sparking from the brushes (as well as rough running sound I could hear) are typical signs of a bad motor, i.e. partial shorting in its windings so it is drawing excessive current. Trying to remember again my motor current measurement about 5 years ago, I now think it was actually about 50-70 mA when bench testing and you measured about 150 mA (which I confirmed as same as what I measured but I think I was wrong). The AC ECU probably detects this overcurrent and cuts the motor off.

It is strange that the pot suddenly lost resistance as it is not connected to the motor in any way; possibly damaged by the previously modified wiring or it has just worn out. If the pot was good, you could probably easily replace the motor with a motor from the fresh air flap actuator but these seem to also have gone up in price (GBP 105 at Eurospares and I don't see any cheap used ones).

 

Just found a picture of the internals of the fresh air actuator - the motor and gears arrangement look quite different from what your video shows so transplanting the motor seems not really possible.
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In the case of my (348) air direction actuator, since my AC ECU was bad and I completely modified it with my new simple circuitry, I am running the motor using two mini relays (for the change of rotation direction) and two of the buttons (as momentary switches) on the ECU panel to activate the relays, one for up and one for down, setting the air direction by feel. To prevent the motor stalling by the actuator hitting its ends of travel, I have attached two mini limit switches to cut the power to the motor off somewhere before the ends of travel.

 

John, the air direction flap is not going to the desired position (automatically or manually). Initially, wiring checks on the actuator seemed ok, so the wiring between the ECU and actuator (and between the ECU and the control panel) were carried out (all ok). The ECU chip which drives the air direction actuator has been replaced. The ECU has not been interrogated. Smoke has been coming from the actuator and subsequent wiring checks of the actuator have shown a lot of intermittency.

Andrew, do you have the part number of that Johnson's(?) motor? It looks like the company is still in business.

 

The fresh air flap motor actually comes in two varieties. They look the same from the outside but the guts are very different. Totally different gear train. One has a worm gear on the motor, as pictured above, the other type has a spur gear on the motor.

As for the current problem, As I suggested pages ago, put it back together and take it to someone with an SD1 or SD2 and have a proper diagnoses performed.

 

Andrew lives on a small island How he got the car there in one piece is a mystery. Those car ferry ramps must be a nightmare.

 

Put it on a truck.

 

Just found my picture of both:

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John, are you sure that's the air direction actuator (on the right)? The air direction actuator should have 5 wires (2 for the motor, 3 for the potentiometer) and has different coloured motor wires. Your two actuators have the same wire colours (light blue-brown and brown).

Here are Andrew's wire colours:

https://www.ferrarichat.com/forum/posts/146306075/

 

No, these are the air flap (recirculation flap) motors. What Miro was talking about in post 130. Sorry for the confusion.

 

I am doing something similar. In my case it is the heater valve that is not functioning. The actuator motor and pot are fine but the ECU isn't responding (bad chip?). But not to worry, it's a spider and I don't need heat but I want to be able to open the heater valve for coolant changes. So I'm using a window switch to energize the motor and a small digital voltmeter hooked up to the pot to tell me the position of the valve until I can get the ECU repaired (or not).

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There are (still expensive) alternatives to SD1/2, but I believe they don't cover all functions on the F355. Anyway, it's unlikely anyone has the alternative on the Isle Of Wight. There are companies which repair/test the ECUs, and I assume, interrogate the fault memory. However, from your description of the actuator potentiometer, I think you've pretty much narrowed down the fault.

(Often repeated story, but... ) I bought a new engine harness from Eurospares (at great cost) and discovered it was faulty from the factory. No returns. By the way. this policy of no returns on electrical components is not unique to Eurospares. My technician spent a day and a half trying to figure out why my engine wouldn't start after a major service.. and it cost me a fortune in labour fees... and would have cost me more if I hadn't volunteered to personally test all the wiring in the new harness and fix the problem. Eurospares contacted Ferrari regarding the problem, but there was no feedback.

As a child, my parents used to take me on holiday to the Isle of Wight (Shanklin), so I have some recollection of the ferries

 

Possibly, but lawyers are more expensive than Ferrari technicians ) and, for me, life is too short to worry about these things. Also, after paying UKP15,000 on gearbox repairs in that same year (previous owner negligence), it was a drop in the ocean. Being a retired avionics technician, I enjoyed dusting off my multimeter and getting to roadtest my coloured Ferrari wiring diagrams )
Anyway, we digress.

It's rather disappointing that the potentiometer is not accessible. It's a shame it wasn't like this type (start video at 3:55) :

 

That's more Miro's forte' .... I never got into the design aspect. He sounds like a busy man, though (with his new MAF project). Also, any designer would need to look at the old actuator and tambour to see what was possible. I'm not sure you could install limit microswitches inside the actuator case, and access to the moving parts inside the tambour would be impossible. You might need to install some kind of cam on an extended actuator drive shaft and mount limit microswitches on the side of the tambour.

I'm wondering if a manually controlled blend door actuator would confuse the ECU if it sensed that air was not going in the right direction at the right temperature... and start shutting things down.

 

This is a picture of the limit switches I installed at the Fresh Air actuator. I attached the switches to the heater/evaporator housing and added a thin aluminium arm (with a square hole) that goes onto the actuator's square shaft. I made the arm as a "fork" so that I could bend them to fine tune the flap end positions.
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In the case of my air direction actuator, I used a similar aluminium arm but smaller limit switches which I attached to the actuator body (on the outside). Unfortunately, I did not take any pictures. As my dashboard is dismantled at the moment (repainting my sticky vents), I will try to get a picture (if possible) of my installed air direction actuator and post later.

 

Why would you need them of the air direction actuator? It's a servo motor and there are no mechanical stops on the air direction vent. Rotation and power to the motor stops when the HVAC ECU reads that it is in the desired position. No?

By the way, these air direction actuator failures are far from unique to Ferrari. Just google Blend door actuator.

 

My recirc flap would not work. Like you my plastic lug was fine (see it in the pic) and the motor ran you could hear it. I pulled the motor and it spun fine both directions. So I cracked it open. When you turn the big gears with the hand I noticed sometimes it would jam, In fact I could get it to to it every time if I put it under load. Turns out some teeth chipped off and that would cause it to lock when it hit that section. The gear was so brittle I cold chip teeth with my nail and parts would get caught int eh teeth making it worse. Bought a new motor and brass lug for good measure, lubed the door and back together it went, works like a champ.

Motors are cheap, buy a few replace every 5 years.

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Because my AC ECU was "dead on arrival" - a number of the traces on the PC board were burnt and, when I re-connected them, I had one of the large IC-s getting very hot. So, I built this:
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I just checked my actuator potentiometer (with a Fluke meter and it was 2261 ohms. At various flap positions, the sum of the two potentiometer sections Green to Violet-Black and Yellow to Violet-Black) was 2326 ohms. Not sure where the extra 65 ohms was coming from. The Fluke meter read "0.0" with the test leads shorted together.

No smoking evident )

 

Obviously, 1+1 is not 2. The difference is probably from some additional resistance when measuring to the wiper (twice). So, it appears to be a 2.2 K pot (fairly standard value) but I believe it is linear and that it has the "wipe" angle smaller than the usual ~300 degrees. The only linear pots I found that have less than the standard wipe angle are 5K 120 and 188 degrees. I don't think the use of 5K (instead of 2.2) would be an issue as the ECU looks for the voltage from the pot, not the resistance. However, the wipe angle is critical - if not identical to the original pot, the air flap would stop at wrong positions.

The 120 & 188 pots: https://www.ebay.com/itm/B5K-5K-Linear-Taper-Potentiometer-for-RC-Transmitter-Control-120-Degree-Rotation/252527810513?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649 , https://www.ebay.com/itm/B5K-5K-Linear-Taper-Potentiometer-RC-Transmitter-188-Degree-Rotation/263075940016?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649