348 HAVAC problem. | FerrariChat

348 HAVAC problem.

Discussion in '348/355' started by Reddesire, Aug 28, 2016.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. Reddesire

    Reddesire Formula Junior

    May 7, 2008
    388
    Melbourne, Australia
    Full Name:
    Andrew Gaal
    G'Day All

    Been a while since I've been on Ferrari chat but now I find myself with a puzzling problem.

    My HAVAC works perfectly except for one thing. The fan speed function will only work on the final 100% setting. In turn the fan won't come on at all for any of the lower settings. Everything else works fine with no dimming issues or other that I can see.

    I've pulled the dash apart and re-seated the connectors on the back of the HAVAC and also pulled off the boot cover and checked and re-seated all the connectors I could see around the AC unit and the relays/fuses on the fuse board in the luggage compartment. My questions are..............

    1/ How can I confirm that it is in fact a HAVAC issue

    2/ Can you buy a HAVAC unit from anywhere for the 348 (I see nothing on eBay) and/or get them repaired by anyone ?

    Best Regs from Oz
     
  2. m.stojanovic

    m.stojanovic F1 Rookie
    Silver Subscribed

    Dec 22, 2011
    2,743
    Malaysia - KL
    Full Name:
    Miroljub Stojanovic
    #2 m.stojanovic, Aug 28, 2016
    Last edited by a moderator: Sep 7, 2017
    There are two things that could have failed:

    1. The digital potentiometer (integrated in the AC ECU) or
    2. The Fan Speed Cotroller (attached to the left side of the evaporator box, accessible from the boot).

    To diagnose which one, you need to access the Fan Speed Controller and disconnect the smaller connector (marked with 4,5,6 on the drawing). Attach a voltmeter between the ground and the socket for pin No. 6 (violet wire), switch the ignition (and the AC) on and see whether you get voltage variation from 0 to 5 V as you press the down and up buttons for fan speed on the ECU. If you do, then the problem is in the Fan Speed Cotroller; if you don't, then the problem is in the ECU itself.

    I think there is a company that repairs 348 ECU-s (others will inform). If you find that the problem is in the ECU, instead of repairing it, you can install a standard potentiometer with a turn-knob and wire it as shown on the drawing (leave the side of the cut violet wire that comes from the ECU unconnected).
    Image Unavailable, Please Login
     
  3. fdekeu

    fdekeu Formula Junior

    Jun 19, 2008
    582
    Belzium
    Full Name:
    Frank
    The fan controller is a Fiat part
    BC 90225
    Also used on some Alfas (155 eg)
    Should not be too difficult to replace this

    You can find it at the drivers side of the ventilation box
    It is integrated in the box so you only see the connectors
     
  4. 97 Spider

    97 Spider Formula 3
    Rossa Subscribed

    Dec 15, 2012
    2,241
    Texas
    Full Name:
    Brian
    Wow, this is great info perfectly explained. Thank you.
     
  5. m.stojanovic

    m.stojanovic F1 Rookie
    Silver Subscribed

    Dec 22, 2011
    2,743
    Malaysia - KL
    Full Name:
    Miroljub Stojanovic
    #5 m.stojanovic, Aug 28, 2016
    Last edited by a moderator: Sep 7, 2017
  6. 4rePhill

    4rePhill F1 Veteran

    Oct 18, 2009
    8,178
    Worcester, England
    Full Name:
    Phill J
    "Should not be too difficult to replace"? - You must be joking!

    Guess what used to fail on a regular basis on the Alfa Romeo 155? (as well as on the Ferrari 348) - The fan speed controller!

    Just about the entire supply of fan speed controllers, both new and used, got used up years ago by both Ferrari and Alfa Romeo owners! - Trust Me, these things are now as rare as a Ferrari F1 World Championship!

    (It took Me two years to find one for sale to have as a spare, and it wasn't cheap, but it was a "must have - Just in case!" part).


    And just to add to the problems with finding a replacement speed controller, there are two versions of the speed controller (both of which use the same part number! - Trust FIAT! :rolleyes: ), one with five terminals (three flat blade connectors and two round pin connectors), and another with six connectors (three flat blade connectors and three round pin connectors) - The 348/355 requires the six connector version (The five connector version is of no use!)
     
  7. Reddesire

    Reddesire Formula Junior

    May 7, 2008
    388
    Melbourne, Australia
    Full Name:
    Andrew Gaal
    #7 Reddesire, Aug 28, 2016
    Last edited by a moderator: Sep 7, 2017
    Fantastic guys, thanks so much for the detailed summary.

    With regards to access hmmmmm I can see it and get one finger to it but it looks like I need to disconnect the rubber water lines surrounding it to get to it.
    My car is RHD so not sure if you guys have the same setup but this part is caged in by the rubber water lines on mine ( see pic)

    If I do that wont water go everywhere when I turn on the ECU and it in turn turns on the water pump for the heater ? I guess I need to disconnect the electric motor first on that as well !

    Any easier way to get to this that I am not seeing here. Would like to avoid water going everywhere in my boot if possible ?
    Image Unavailable, Please Login
     
  8. Reddesire

    Reddesire Formula Junior

    May 7, 2008
    388
    Melbourne, Australia
    Full Name:
    Andrew Gaal
    Also you mentioned there may be someone who repairs the ECU's. If it turns out to be that does anyone know of this repair company/person.

    Looks like either way its going to be a hard fix :(
     
  9. ///Mike

    ///Mike F1 Veteran

    Dec 11, 2003
    6,097
    Bugtussle
    The company that repairs the HVAC ECUs was mentioned here not long ago. I remember one poster said they repaired his and it worked fine for a short time but started acting up again after a short time. If he followed up on that I didn't see it so not sure what the eventual outcome was. I'm just glad someone is working on them.

    I might have a note at home, in which case I'll try to post the info but you can also check the archives and you'll find it.
     
  10. m.stojanovic

    m.stojanovic F1 Rookie
    Silver Subscribed

    Dec 22, 2011
    2,743
    Malaysia - KL
    Full Name:
    Miroljub Stojanovic
    Has anybody cut-open the fan Controller? Are the parts inside accessible or are thay sealed in epoxy?

    I would like to try to repair the controller but I don't have a non-working one. Anyone having / willing to send me a bad controller? Some time ago I fixed a similar controller on a BMW 635Csi - put in a more powerful transistor to make it much more robust.
     
  11. fdekeu

    fdekeu Formula Junior

    Jun 19, 2008
    582
    Belzium
    Full Name:
    Frank
    #11 fdekeu, Aug 29, 2016
    Last edited by a moderator: Sep 7, 2017
    Found this on an Alfa forum
    Looks like it must be possible to repair it
    Mine are OK so cannot send you one
    Image Unavailable, Please Login
    Image Unavailable, Please Login
     
  12. fdekeu

    fdekeu Formula Junior

    Jun 19, 2008
    582
    Belzium
    Full Name:
    Frank
    LHD Cars have the same setup
    I would try to disassemble it without disconnecting the waterlines
     
  13. m.stojanovic

    m.stojanovic F1 Rookie
    Silver Subscribed

    Dec 22, 2011
    2,743
    Malaysia - KL
    Full Name:
    Miroljub Stojanovic
    Great info Frank. In this case, the unit should be easily repairable provided that the IC is available (sometimes they are custom made only for the unit manufacturer). However, most probable cause of the malfunction is failure of the power transistor that controls the blower speed which can easily be found, same or equivalent. More powerful one can also be installed.

    Andrew, looking at the circuit board picture posted by Frank (and noticing the relay), I am now almost certain that your controller has failed, not the ECU (lucky for you). The power transistor controls the fan speed from zero to about 95% and then the relay is activated to bridge the transistor and provide full speed. A relay is used for the full speed in order to save the transistor from being overloaded at the full current. Since you can get the full speed, it means that there is a good signal from the ECU which, via the Controller's electronics, triggers the relay when you set the speed control on the ECU close to full speed. What is missing is the gradual speed regulation up to the relay trigger point. This means that the power transistor (or some other smaller component controlling the power transistor) in your Fan Speed Controller has failed.
     
  14. 348Jeff

    348Jeff Formula 3

    Oct 25, 2011
    1,496
    UK
    Full Name:
    Jeff
    I've swapped over my power transistor - right pain to get at it - see below for photos of removing from a RH drive car

    348 DIY "Restoration" - Page 154

    BTW I replaced mine with a 355 one but just be aware there are 2 different types with different amount of pins.

    In my case it didnt solve my problem but did improve it ie after a while the "melted fuse" that I replaced with a breaker would trip out if I ran the fa at more than 4 bars on the HVAC
     
  15. 4rePhill

    4rePhill F1 Veteran

    Oct 18, 2009
    8,178
    Worcester, England
    Full Name:
    Phill J
    The 348 and the 355 both use the same fan speed controller - With three blade connectors and three round pin connectors.

    (Again, if it's only got two round pin connectors then it's the wrong one, despite carrying the same part number as the version with three round pin connectors).
     
  16. fdekeu

    fdekeu Formula Junior

    Jun 19, 2008
    582
    Belzium
    Full Name:
    Frank
    #16 fdekeu, Aug 30, 2016
    Last edited by a moderator: Sep 7, 2017
    Here is the module out of my 348TS LHD
    No big problem to get it out
    Got the front off but cannot pull the pcb out
    Afraid of braking it
    Since they are so hard to find
    Image Unavailable, Please Login
     
  17. m.stojanovic

    m.stojanovic F1 Rookie
    Silver Subscribed

    Dec 22, 2011
    2,743
    Malaysia - KL
    Full Name:
    Miroljub Stojanovic
    The power transistor (below the PCB) is most probably screwed to the cooling fins. To get the PCB out, I believe, you have to de-solder the three pins of the transistor as you pull the PCB out. Of course, don't do it on good unit.
     
  18. fdekeu

    fdekeu Formula Junior

    Jun 19, 2008
    582
    Belzium
    Full Name:
    Frank
    It works allright
    Although the whole system does not work as it should
    There must be a bad connection somewhere because the heater
    starts working full power now and then
    The only way to stop it is by turning off the ignition
     
  19. Reddesire

    Reddesire Formula Junior

    May 7, 2008
    388
    Melbourne, Australia
    Full Name:
    Andrew Gaal
    Wow thanks guys this is a far greater response that I could have ever imagined and have learnt allot here. Clearly there is a huge demand from people who no doubt would be prepared to pay a reasonable fee for the repair of this. A shame no one has put their hand up to offer this obviously much needed service.

    Have also found a string where someone posted pics of them removing the controller. It does look like you need to disconnect at least one pipe and then move the other to one side with a bit of gentle persuasion.
     
  20. Reddesire

    Reddesire Formula Junior

    May 7, 2008
    388
    Melbourne, Australia
    Full Name:
    Andrew Gaal


    When I pull mine out and test it and confirm it is dead then I shall get in touch and we can have a chat about possible options !
     
  21. Reddesire

    Reddesire Formula Junior

    May 7, 2008
    388
    Melbourne, Australia
    Full Name:
    Andrew Gaal

    So good to read this. I hope so as we all know what another ECU would cost me should one EVER surface. Last one I saw on ebay sold for nearly EUR 2,000 second hand !
     
  22. fdekeu

    fdekeu Formula Junior

    Jun 19, 2008
    582
    Belzium
    Full Name:
    Frank
    If mine turns out to be defective I plan to use an Arduino to replace the cpu
    using the same front
    less than 100 euro in parts for sure
     
  23. whyte

    whyte Formula Junior

    Apr 25, 2006
    404
    Merritt Island, FL
    Full Name:
    John C
    With a heat sink like that, and all that vibration, it would be worth checking for cracked solder joints or shorts as well.

    I've been chasing this issue for years as well. It's one of those that is a pain, but not usually a big enough pain to warrant the work, especially when I have the top off 99% of the time. I've often wondered if the controller is failing because the resistance on the blower motor is too high, due to either worn bearings, loose connections, etc. Really need to get a scope on all the inputs, check the resistance on the load. It is quite possibly a series of issues, not one isolated problem.

    Assuming that the controller is bad, there are many cheap solid state fan controllers these days. I wouldn't be surprised to find one that has a similar speed control interface, or at least, one that could be adapted easily. Something in this ballpark:

    12V 24V Max 20A PWM DC Motor Stepless Variable Speed Control Controller Switch | eBay

    The workshop manual provides the following info on the Power Control Module (OCR scan and translated):

    "A power module controls the fan speed
    varying the voltage of the fan motor. The
    module is divided into 2 sections, one is
    for low current control, the other for power
    control,-see fig:7: The unit gives its information
    about its temperature by means of
    the voltage of the pin No.5 and regulates
    the voltage at the pin No.2 according to
    the signal sended by the ECU (.pinNo.6).
    Internally the NTC temperature sensor (thermistor?) is
    responsible for the thermal protection of
    the power module."

    It is worth mentioning that the 348 A/C ECU has a built in diagnostic function, and there is a specific error for issues with the Fan Speed Control Unit (E7). Although the manual shows the use of the Ferrari test tool, I think you can run the test without the tool as well.

    Hope some of this helps!
     
  24. m.stojanovic

    m.stojanovic F1 Rookie
    Silver Subscribed

    Dec 22, 2011
    2,743
    Malaysia - KL
    Full Name:
    Miroljub Stojanovic
    Yes, let me know when you establish whether you have a 0-5V (should be about 2.5 volt when you set the bar display on the ECU to half-way) signal on the violet wire coming from the AC ECU. I can then send you a simple diagram showing how to bench test the removed Speed Controller to re-confirm its condition (if you prefer, you can straight away just remove the Controller and bench-test it). If really dead, then one option could be that you send the Speed Controller to me (Malaysia, Kuala Lumpur) and, if I can fix it, you pay only for the parts (probably just a few dolalrs) and the shipping back to you (not expensive from Malaysia by registered mail).
     
  25. fdekeu

    fdekeu Formula Junior

    Jun 19, 2008
    582
    Belzium
    Full Name:
    Frank
    Thanks for that input
    I think 20Amps is not enough since Jef348 has measured the max current as 20 amps
    Probably a bit more is needed to be on the save side

    I had error E7 once but the unit is still working ok
     

Share This Page