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F355 HVAC ECU

Discussion in '348/355' started by baschul, Jun 28, 2016.

  1. brendon0

    brendon0 Formula Junior
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    Dec 13, 2003
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    Awesome.

    Can you share with us how you did the diagnostics on the temperature sensors? This
    is one step I did no complete and am curious how it is done.
     
  2. baschul

    baschul Karting
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    May 27, 2015
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    #77 baschul, Feb 24, 2017
    Last edited by a moderator: Sep 7, 2017
    I used an ohm meter to test resistance based on the current temperature and the correct revised resistance when the temp was slightly elevated using a heat gun at a distance. The attached chart that shows the resistance for each sensor by temperature reading and was provided in another FChat thread by m.stojanovic.
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  3. dr fabio del rio

    Dec 4, 2015
    7
    I have problems with the AC heater ECU fan comes on full with full heat I am rebuilding the ECU and replacing the bad TCA2465G power amp chips can anyone tell me what parts of the system are controlled by each of the 6 chips ? I saw a thread on this but it ran cold thanks your help is much appreciated
     
  4. Qavion

    Qavion F1 Rookie

    Feb 20, 2015
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    Are you saying the HVAC system always give you high heat and high fans speeds (even though you've selected cold)? Or are you saying the fan runs fast when you select higher temperatures only?
     
  5. Qavion

    Qavion F1 Rookie

    Feb 20, 2015
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    Just wondering how you know it's the ECU. Have you tried a new one?

    Why would two driver chips fail? Wouldn't it more likely be a faulty CPU or one of the sensors sending false information to the ECU?

    3 of the 6 chips have been identified (see message #67 above):

    If you have the time (and your car is in pieces), can you find out which pin on the yellow plug corresponds to the ECU fan (speed) control output? If you can trace this to a chip, that will most likely be one of the chips you are looking for. According to the Workshop Manual (WSM), the fan speed command from the ECU goes to a pin labelled "6" on the Fan Power Control Unit (refer to the HVAC section in the WSM Volume 3, I-26. If you can match the wire colour on this pin 6 of the Fan Power Control Unit to the same colour wire going to one of the ECU pins, that will give you a good start. Note: Using Fig 6 of the Wiring Diagrams, I've narrowed it down to either pin 8 (purple/white wire) or pin 20 (purple wire). I can't pinpoint the exact pin number because I don't know if the WSM numbering system in the HVAC section (I-26) corresponds to the pin order in the wiring diagrams.

    In the following diagram, I've labelled the pins on the Fan Control Power Unit plug "B" (temporarily) "4, 5, 6", but I don't know if the colour sequence on the car is Black, Purple-White, Purple... or Black, Purple, Purple-White.

    http://www.members.iinet.net.au/~b744er@ozemail.com.au/FerrariF355Spider/Fig6_Cooling_Circuit_&_AC_System.gif

    Hope this helps
    Cheers
    Ian.



    Perhaps if someone has their luggage compartment in pieces at the moment, they could tell us the wire colour sequence on the Fan Control Power Unit?
     
  6. Qavion

    Qavion F1 Rookie

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    #81 Qavion, May 13, 2017
    Last edited: May 13, 2017
    Just wondering how you know it's the ECU. Have you tried a new one?

    Why would two driver chips fail? Wouldn't it more likely be a faulty CPU or one of the sensors sending false information to the ECU?

    3 of the 6 chips have been identified (see message #67 above):

    If you can trace the fan control speed signal ECU yellow connector pin to a chip in the ECU, that will most likely be one of the chips you are looking for. According to the Workshop Manual (WSM), the fan speed command from the ECU goes from ECU yellow plug pin 20 to pin "6" on the Fan Power Control Unit (refer to the HVAC section in the WSM Volume 3, I-26). It's a purple wire.

    http://www.members.iinet.net.au/~b744er@ozemail.com.au/FerrariF355Spider/Fig6_Cooling_Circuit_&_AC_System.gif

    (EDIT) I previously wasn't sure of the pin order on the Fan Power Control Unit plugs, but I've confirmed that my diagram is correct by checking my car's wiring.

    Hope this helps
    Cheers
    Ian.

    P.S. I'm starting to wonder is the Fan Control Power Unit even needs a driver chip. The function of the Fan Control Power unit is to boost a weak signal from the ECU to one which will control the fan speed.
     
  7. Skiday

    Skiday Karting

    Feb 22, 2016
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    This sums up my situation exactly. I have my own thread here; https://www.ferrarichat.com/forum/threads/new-owner-with-ventilation-problem.514304/page-2

    Thank you for taking the time to put all this down. It is proving very helpful. It goes to show that car are just too damn clever for their own good these days! Anyway. I haven't found the chips so cheap, only for over £35 each, but located in London. So I'm getting one and replacing just chip No.6 and hope that works.

    Incidentally, you say that you tested the control unit. How did you do that? I've had mine open for a visual inspection and all looks good, but I can't be totally sure that it is (although everyone's problem seems to turn out to be the ecu chip). I wonder what is causing these chips to fail for so many people. There must be a weak link somewhere.
     
  8. Qavion

    Qavion F1 Rookie

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  9. cheungchoyui

    cheungchoyui Karting

    Oct 16, 2016
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    Did the chip solve your problem finally ?


    Sent from my iPhone using FerrariChat
     
  10. brendon0

    brendon0 Formula Junior
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    My ECU rebuild worked perfectly. All systems functional.

    Really you can test these with a voltmeter if you have the time.
     
  11. cheungchoyui

    cheungchoyui Karting

    Oct 16, 2016
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    Joe Cheung
    Hi,

    Assuming I have taken out the ECU board , what are the procedures to test if the chip is bad by voltmeter ?

    Thanks



    Sent from my iPhone using FerrariChat
     
  12. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
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    TUV requirement. When system fails it is supposed to default to that mode of operation for safety.
     
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  13. brendon0

    brendon0 Formula Junior
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    I dont know how to test with the board out. I just had my guy replace all 6 chips.

    If the ECU is in, you can measure voltage at the motor connector levels.
     
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  14. Shurik355

    Shurik355 Karting
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    May 19, 2013
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    Alex Velet
    So now Im in the situation of fixing my HVAC! :confused:

    Found out my drive boss for the flap is broke, and need fixing or replacing. My heater valve wasn't even plugged in for some reason when I got the car. (Just found out recently)

    Been reading these threads and trying to figure out as I go whats what. Might most likely replace the bad chips in the AC ECU as well.

    What exactly does that hidden AC 30amp fuse does??? its not blown but it was getting hot there that the plastic around it was melting.

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  15. Qavion

    Qavion F1 Rookie

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    The 30 Amp fuse is basically for the heavy duty stuff, such as the fan motor (in the luggage compartment) and the aircon compressor clutch. Some voltage also goes to the HVAC ECU, but it may be only to let the ECU know there is power available (I'm not sure if it powers the ECU itself).

    If the fuseholder is melting, it might just be old age or a sign that the components are drawing too much power. Hopefully the former.
     
  16. Ricambi America

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    drbob101, baschul, Shurik355 and 2 others like this.
  17. WATSON

    WATSON F1 World Champ
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    Sep 9, 2010
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    Some of us have replaced that 30 amp fuse and holder with a bullet style holder/ fuse that does not melt the housing like the current design has a tendency to do.
     
  18. brendon0

    brendon0 Formula Junior
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    Hey Guys,

    I just went thru a nightmare fixing my HVAC again. The 30 amp fuse was blowing constantly. Eventually gave up and took
    it to exotic auto in Clearwater and Gabe got it sorted out.

    Turns out my blower motor had extremely high resistance so turning the fan to "4" would blow the fuse. Ended up having to pull
    the entire HVAC unit out and replace it with a used part.

    Once that was put in my compressor was not working. That was diagnosed as a short on the electro-magnet. Ended up replacing
    the whole compressor and dryer as well.

    Pumping out ice cold air now. Had the windows tinted too so the car is my daily in Florida from now on.

    They also replaced the main cable for the system and put in a heavier fuse holder so there is no more overheating.

    If you are getting alot of heat in the cable and fuse holder you have major resistance somewhere.

     
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  19. Ari Paul

    Ari Paul Rookie

    Sep 18, 2018
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    Hi! Where is the HVAC ECU located??!! I am trying to remove mine to fix it and I can't find location or instructions anywhere!

    Thanks.
     
  20. Qavion

    Qavion F1 Rookie

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    #95 Qavion, May 4, 2020
    Last edited: May 4, 2020
    It's in the forward luggage compartment. You have to remove the liner (carpet/felt) which sits in front of the windscreen. The ECU is mounted vertically to a metal bracket near one of the bonnet latches (I can't remember if there are variations between left hand drive and right hand drive cars so I won't specify the side it's on).

    You may find the windscreen wiper ECU ("intermittency unit") mounted in the same area.

    It may be easier to remove the mounting bracket than the ECU (?)

    I don't know if you've removed the luggage liner before, but you need to remove the rubber seal, the metal rub strips, the surround to the fresh air/blower motor assembly (4 screws), the fusebox cover (and its counterpart) and numerous screws holding that liner piece to the side pieces. On my car, it's a bit of a jigsaw puzzle and it helps if I remove the side pieces, noting that these pieces are rather fragile. Some folks can remove the windscreen section without doing this.

    Don't drop the screws for the fresh air inlet surround into the holes in the assembly as you may never find them again.
     
  21. Ari Paul

    Ari Paul Rookie

    Sep 18, 2018
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    Man, you're awesome! That was so helpful and so quick!
     
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  22. Qavion

    Qavion F1 Rookie

    Feb 20, 2015
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    You're welcome )

    Here's a photo of the ECU location on a LHD car (thanks to Eric).

    https://www.ferrarichat.com/forum/posts/137388399/

    I just used the F348/F355 Forum Search (searchwords HVAC, ECU, where) to find it.
     
  23. Ari Paul

    Ari Paul Rookie

    Sep 18, 2018
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    WATSON,

    Did you ever get your A/C working???
     
  24. Ari Paul

    Ari Paul Rookie

    Sep 18, 2018
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    Ari Paul
    Hi everyone:

    I can confirm that I too just did this HVAC ECU repair (replacing all 6 TCA2465G microchips) and my system now works!

    I was a bit skeptical when I first read about this online, but when I took it into my electronics repair guy, he looked up the factory specs of the chip and immediately said "oh, of course these chips went bad, they're amps!" Since I don't understand a thing about electronics I asked him to explain in simple terms. He explained that over time, based on the configuration of the chips, they will go bad due to heat cycles, especially since they didn't come with any heat sinks. He discovered that the manufacturer offers a heat-sink version of these chips (with metal fins on top) but speculated that Ferrari didn't put them on either because they weren't available at the time, or it was planned obsolescence...

    Anyway, I hope my experience helps anyone else who is on the fence about this.
     
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  25. Qavion

    Qavion F1 Rookie

    Feb 20, 2015
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    Looking at the datasheet for the chip, it looks like the ones with the heatsink have a different type of mount. I guess the repair guy fitted the standard ones?
     

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