F355 heater/ac control ecu

The ecu is in the front trunk, passenger side on lhd models, hidden by the felt liner. The felt liner comes out in sections (it is held by numerous screws); the rubber seal also has to come out along with the metal surround to the hvac intake in the center. The ecu is not an "off the shelf" Bosch product, unfortunately, nor is it a "Ferrari universal" product, though it is made by Bosch. Unfortunately, in their great wisdom, Ferrari chose to use a unique ecu for the 355. This was not used for any other models, so it will be as expensive as that sounds. Apparently these go bad with the slightest amount of moisture, so any water gets in there, it may be bad. Not uncommon. Don't know the current prices, but when mine needed replacing it was $1600. Ricambi will have them, though you may be able to source one out of a junkyard (I tried for a while, without luck, and bit the bullet to get my a/c back).

Good luck,

John

 

Just to confirm: You have triple checked the button on the console that says "stop"?

 

First, disconnect battery power. In that way you reboot the A/C ecu, which often fixes them (they get confused just like any other computer).

Second, if the problem persists, check the cockpit temp sensor. Much cheaper to replace it instead of that A/C ecu.

Perhaps your 355 also has the same on board diagnostics in that A/C ecu as the 348 has. On the 348, we can use the A/C ecu to test each actuator and sensor. There is a diagnostic mode on the ecu.

If it was me, I'd change that hot water valve before the A/C computer, too!

 

no

no

no

no

ECUs are junk, go bad often, probably sell 5-6 per year

 

It sounds as though you've had good success changing parts out.

 

Not at all. I have good success systematically and carefully diagnosing problems for my customers and selling them the correct parts without unecessary expense to them.

I leave the parts substituting to others. See the thread about non return of electrical items at ricambi and everybody else in the industry.

Of course, I am sure OP would happily have you supply him the things suggested to try.

 

First, I'd refer to the Ferrari factory workshop manual. Where you say "no," the manual says "yes."

Here's the manual:
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My first suggestion to the OP was a free test/fix. Turn off the battery power with the round black disconnect knob. This *absolutely* fixes some of the Borletti controlling A/C computer on 348s, and may fix the Borletti controlling computer on 355s.

 

The Heater Control Valve is made up of two removable, individual components: a small electric motor and a plastic valve.

The silver/metal electric stepper motor on top of the heater-control-valve is Bosch part #0 390 721 006, which is the Saab 9000 P/N 9625435 at ~~ $139.00 (always good to be able to walk into a local Saab dealership for parts when you don't have a Ferrari dealership in town). A cheaper one is here online: http://www.importpartsspec.com/cart/list/category/HVAC:Heater+Servo


The black plastic valve second half of the HCV (pencil is touching it in picture) costs $13 new: http://oem.thepartsbin.com/parts/thepartsbin/quote.jsp?make=VW&year=1992&product=R3020-17778&application=000187784&part=Heater%20Valve&category=All&dp=false


FYI: the Ferrari part number for the two parts combined is: 63306400 (#8 in diagram below)
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If you know someone else near you who also has a 355, ask them to simply allow you to try his (or her) ecu in your car. If that solves the problem then you have your answer. This is how I knew that my problem was the ecu... rest of system worked fine. Then when I bit the bullet & bought the very expensive ecu, at least I knew this would solve the problem definitively. Been trouble-free for 2 years now. I definitely agree with Brian S that these things seem to go bad frequently. My tech tells me these cars are very water-sensitive, and that things like this (and cat ecu's) just seem to go bad more the more the cars get wet. Easy for me to keep my car dry in SoCal, but I feel for you brothers in the wetter climes.

Good luck with the fix.

John

 

I am not willing to "throw" parts at my customer's cars, even if they are only $139 cost. Using your diagnostic technique the final bill could be easily doubled.

 

Hmmm... How much do those A/C ecu's cost?

 

When I was in the market, ecu was $1600!!! Kinda like gold, I don't know today's price, but I am sure it fluctuates with currency exchange, global demand, etc.

John

 

I have located a Company in Rogersville TN called Automotive Scientific Inc tel No. 1-866 982 6688> they have experience rebuilding the ECU. It costs about $280 US plus shipping. You need to go unto their site, to download a shipping form which needs to be filled out and sent with your unit. A lot cheaper than buying a new one and better than getting a used one from a scrapped vehicle.