A/C control switch in F355

I am currently in the middle of diagnosing this exact problem in mine.

Based on my search here....NOBODY has been able to figure out why this happening.

I sent my divertor motor to an FChatter to test and it's good. I also installed a working HVAC control box in the middle console but that didn't fix the problem either.

So...it looks like I'm going to and the ECU in to someone to test on their 355. hopefully this week.

http://ferrarichat.com/forum/showthread.php?t=371843


http://ferrarichat.com/forum/showthread.php?t=329976

 

I think it has something to do with the battery having been turned off and then when the battery is turned back on, it is stuck on defrost. This happened to me after I had turned the battery off. I think that the A/C computer gets out of sync but I don't know how to get it back in sync. I know with other cars, there is a specific procedure to resync the A/C.

 

I recently went through this. There is a stepper motor that controls the "where air goes" vane in the heat/A/C box. The stepper motor has died.

 

yeah, those motors die and plastic pieces also break, happened on my 348.
you can turn the ignition on without starting the motor and test the a/c controls.
I kept hearing the stepper motor turning without stopping in a set position to divert the air.

not too difficult to repair.
Ricambi got me the stuff I needed.

 

Are you talking about this?

http://www.ricambiamerica.com/product_info.php?cPath=457_99999&products_id=254040

I think Blampee has replaced this and it didn't help.

I have a little air coming out of my defrost all the time. I haven't dug into much yet but I've been reading everything F355Bob and Blampee say about it.

 

Yes. This piece above did NOT fix my problem.

I sent my above piece to FChatter WATSON and he tested it in his 355 and it works.

(There are no other 355s near Omaha.)

 

Do we have any Ferrari techs who can address this????

 

It is not the stepper motor. I and others have replaced them and still did not work. If I bench test the motor it works fine and moves to all positions. If I connect the motor to the wiring harness and turn the switch to the different air vent positions, the motor shaft will move but then return to the original position. Something is controlling the motor and telling it to take the default position which is defrost. I am assuming it is the ECU. I have replaced the ECU and that did not work. Tested the ECU on another F355 and worked fine. There is a lack of communication with the ECU and the A/C system. It seems like several have developed this problem after disconnecting the battery so some memory or synchronization has been lost.

 

I just sent Dave Helms a link to this thread. That guy is a Ferrari genius. If he can't help us we are all screwed.

Hope he can chime in today.

 

I had the same issue (air only blowing from defrost vents). I took it to Norwood's and they adjusted the diverter flap and cleaned the grounds and wires. It works fine now.

 

Do you know what adjustment they did and were the connections on the harness that goes to the diverter motor or elsewhere?

 

I don't know but I'll ask them to see.

 

That would be great because it seems like Norwood is the only one that solved this common problem.

 

I have not had a chance to look....is there a fuse or relay in the system between the switch and the motor?

Blamp's motor worked fine in my car, but dead in his..... has to be something simple.

 

Hey Guys, this thread kind of petered out last summer, seemingly without resolution. In spite of my search through the archives, I can't find anything further. Did we ever figure out what causes this common problem? I am having the same issues. Thanks, Henry

 

I've had this problem for 2 years. Tried everything, still not fixed. A/C in F355 sucks.

 

R.I.P

 

Just a thought but when I was reading the WSM I believe it says something about the control unit defaults to the windscreen when temp outside is cold or something. Maybe the outside temp is not functioning and giving a false reading. Just trying to think outside the box?

 

Hadn't heard that explanation before Grant. That would be funny if that's what it was all this time. I assume we're talking about the outside temp sensor on the rear view mirror?

 

This is happening to me as well on my 97 355 Spider.

Just got my car back from the engine-out service, and air is only blowing from the defroster vents on the top of the dash. A/C works fine (gets cold), fan speed works fine, but no matter what position the "vent selection" switch is in, air is only blowing from the defroster vents.

From what I've read above, the problem is:

1. Bad A/C ECU. (I'm trying a spare today, we'll see if that works)

2. Bad diverter stepper motor. Mine doesn't move at all with the vent selection switch, so I'm thinking it's bad. However, when I tried a known good one, it just slightly rotates and then returns to the original position.

3. Corrosion on connections and ground points. I'll have to check that out as well.

4. Stuck diverter flap.

5. Outside temp sensor (on rear view mirror?). This is an interesting one; it might explain why a good diverter motor would rotate and then return to the same position. How would I check this out? Is it built into the rear view mirror?

 

An update to the above: the spare A/C ECU made no difference. Neither did a good diverter stepper motor. I never did get to check corrosion on connections/grounds or the diverter flap. I did take apart the left rear view mirror, and the connection to the outside temp sensor seemed fine.

I then disconnected the battery, waited a few minutes, and then reconnected it.

Air is now flowing properly from the correct vents. Everything is working properly. Even my "bad" diverter stepper motor, which I didn't think worked at all, is working fine now.

So, there must be something that is reset when electrical power is removed and then restored.

Hope this helps others out there with the same symptoms.

 

I have tried the battery thing and has not worked in several years after installing new ECU, motors etc. Did you connect and reconnect the sensor in the mirror? If you did, maybe it made a better connection.