Struggling with Heater Valve / Heater Control Testing. Super stumped. | Page 3 | FerrariChat

Struggling with Heater Valve / Heater Control Testing. Super stumped.

Discussion in 'Mondial' started by Albert Penello, Mar 10, 2020.

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  1. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Jan 11, 2001
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    That's what I thought, too -- until reading the 308/84 OM which directly states that heat is possible with the STOP button pressed. Additionally, although not directly stated, the language might imply that heat is intentionally made not possible when using the A/C button (i.e., it is a "summer" button). Consequently, I have to say "that I don't know" ;), but I have to think that heat should be possible in the A/E and DEF positions so Albert's report that the heater valve relay is unenergized when those buttons are pressed seems wacky (as an unenergized heater valve relay always holds the heater valve closed) as does his report that +12V is not present on terminal 86 of the heater valve relay in some cases.
     
  2. mike32

    mike32 F1 Veteran

    May 13, 2016
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    That is about half of them, do you have GR to ZN ? Otherwise i will post them
     
  3. mike32

    mike32 F1 Veteran

    May 13, 2016
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    I dont understand how the control side of this works but in some AC systems they use the cold evaporator to drop the dew point to remove the humidity etc, some systems use what they call reheating using steam coils or electric elements by putting heat back into the air to guard against the conditioned air being too cold going to the room. By chilling the air down low they remove more humidity but too cold to pump into a room. Any chance it is using the heat valve in this way ?
     
  4. theunissenguido

    theunissenguido Formula 3
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    When looking at the diagram figure 11, C has 4 wires connected, M has 4 wires connected and N has 5 wires connected. Means that C and M should be the same number. Not C and N...
    Guido
     
  5. Albert Penello

    Albert Penello Karting

    Jul 21, 2019
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    Steve I think the part in BOLD you have backwards - power ON closes the valve (no heat) and power OFF opens the valve (heat) so I think it's working as you suggest. With STOP pressed, there is 12v to the heater valve which closes the valve so there is no heat. That makes sense to me. When I hit the A/C button, that also has power to the heater valve (no heat) which also makes sense that you'd want to close the valve when you want A/C.

    When I'm at A/E or Defrost, the power goes OFF which would be the case where heat would be enabled. I assume in those cases control transfers to the HVAC ECU allowing for temperature control via the Pot on the dash. So it does seem to work as you had suggested in your earlier post.
     
  6. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #56 Steve Magnusson, Mar 14, 2020
    Last edited: Mar 14, 2020
    I think you are right as (hopefully) I misread your post. When you wrote:

    Ignition on, STOP pressed = Power to terminal 86 on Relay = Light ON at Heater Valve Connector (relay clicks)
    A/C on = Power to Terminal 86 on Relay = Light ON at Heater Valve Connector (relay clicks)
    A/E button pressed = NO power at Terminal 86 = Light OFF at Heater Valve Connector (no click)
    DEF button pressed = NO power at Terminal 86 = Light OFF at Heater Valve Connector (no click)

    what's happening at the heater valve is OK for good operation as you note, but your relay clicking description seems backward (i.e., when the heater valve relay doesn't click = light "on" at heater valve and the heater valve clicks; when the heater valve relay does click = light "off" at heater valve and heater valve doesn't click). When you describe "clicks" or "no click" are you talking about the heater valve relay clicking or the heater valve clicking?
     
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  7. Albert Penello

    Albert Penello Karting

    Jul 21, 2019
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    #57 Albert Penello, Mar 14, 2020
    Last edited: Mar 14, 2020
    So what I hear is the Heater Valve Relay (SIPEA 0440) clicking which I assume is providing the power from the ignition to the heater valve connector.

    I don't have the heater valve connector actually hooked up to the heater valve at this point. I have a light wired in there right now which is helping with the diagnosis somewhat.

    When I turn the ignition ON, I hear the relay click and the light goes on at the heater valve connector was what I was trying to describe above.

    NOTE - rereading your posts again I may be simply misunderstanding what the click is. I'm just saying what I'm hearing, so it's possible as you say that the click is actually the relay turning OFF, not turning ON. I know the 0440 relays work differently, so I think what's most important is what's happening with the light, which follows your guidelines.
     
  8. afterburner

    afterburner F1 Rookie
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  9. Albert Penello

    Albert Penello Karting

    Jul 21, 2019
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    So these posts are helping more to understand what I think is happening but it still leaves me confused as to HOW the HVAC ECU takes the Pot signal for heat and changes the heater valve connector power.

    12v is always on the BR wire. I think I get that. And in the condition of STOP or A/C, the MB wire gets ground from the Pin 87a of the 0440 relay. I think I have this part down.

    So now, when I'm in A/E or Defrost, that MB (brown/white) wire gets a ground signal from the IV pin on the HVAC ECU.

    However, URS diagram has that pin labeled as (-) or Ground. What I read you saying above however is when the POT for Temp control is turned, the IV pin is cycling between power and ground, which is how the light "blinks"

    Am I understanding that correctly? My friend is currently reverse-engineering the schematic for the HVAC ECU (meaning when he's done, anyone should be able to build one) but we were discusing how that unit is supposed to operate.

    Clearly, the POT signal comes in on Pins 6 (HN) and 5 (HR). Somehow, that goes through the ECU and changes something on Pin IV.
     
  10. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Yes, that's correct. While Urs labeled pin IV as "-", it would maybe be more correct to label it as "the minus terminal of the heater valve" which sometimes is at ground to close the heater valve and sometimes at +12V (or nothing) to open the heater valve.
     
  11. afterburner

    afterburner F1 Rookie
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    Here a word to those not speaking Italian - and about the workings of the buttons on the Mondial:

    A/E means "Aria Esterna" as in external air enters the cabin
    A/C mean "Aria Circulata" as in recirculated cabin air
    DEF directs air to the demister vents on the dash, closes the center dash vent and uses external air

    1) The above buttons have NO influence on the workings of the ECU (A/C or heater); they are purely air distribution choices.
    2) STOP closes the external flap and stops the fan.
    3) All buttons have NO influence on the power supply to the ECU - the ignition key powers it up and down.
    4) With either A/E, A/C or DEF pressed, the fan speed will never be zero, even when rotated to the lowest position
    5) Even with STOP pressed, the ecu will regulate the heater valve and A/C clutch
     
  12. afterburner

    afterburner F1 Rookie
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    Ah! I thought about that but if it is at 12V wouldn't it short circuit through the heater valve relay?
     
  13. Albert Penello

    Albert Penello Karting

    Jul 21, 2019
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    So this seems to be at odds with my testing and what Steve is saying. I agree on the fan portion - the fan seems to be independently controlled except for STOP

    However the buttons are clearly also activating and deactivating the relay SIPEA 0440 in my car. I'm using the wiring diagram on Pg 11 for the cars after 43973.

    I have no HVAC ECU in the car right now, and yet pressing the buttons is controlling the light on the heater valve. This would suggest that the buttons do override the ECU in certain cases.

    Perhaps what you're saying works differently in the pre-43973 and post-43973 cars since there are two different wiring diagrams and missing Relays in the earlier cars?
     
  14. Albert Penello

    Albert Penello Karting

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    Not if the relay is disconnecting the ground, which is what he's saying. So it looks like when the relay is energized, the ground is REMOVED, which then switches control over the HVAC ECU.
     
  15. afterburner

    afterburner F1 Rookie
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    OK, right - let me state it more precisely - the OFF button removes power from the 3 HVAC relays but not from the ECU, the sensors and the cabin air suction fan. So the A/C clutch and heater valve won't react to the commands sent out by the ECU.
     
  16. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    I meant that more as the voltage that you'd measure at the minus terminal of the heater valve (pin IV) relative to ground during the PWM cycle when the heater valve is open (not that pin IV is a voltage source). The current in the heater valve coil is controlled by the large transistor in your post #32 schematic:

    When the transistor is biased to allow current to flow from C to E = heater valve closed, and the voltage on the minus terminal of the heater valve (pin IV) would measure ~0 V relative to ground.

    When the transistor is biased to prevent current flow from C to E = heater valve open, and the voltage on the minus terminal of the heater valve (pin IV) would measure +12V relative to ground.
     
  17. afterburner

    afterburner F1 Rookie
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    #67 afterburner, Mar 14, 2020
    Last edited: Mar 14, 2020
    Thank you Steve! All clear now - the relay cuts the ground connection when the buttons are in AC, AE or DEF position so it won't short out. Then ECU can control the valve directly with its power transistor. Clever.
     
  18. Albert Penello

    Albert Penello Karting

    Jul 21, 2019
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    In my testing, it only cuts out ground in A/E or DEF. A/C and STOP are still grounded. Now I'm wondering if there is something wrong with my push button unit.
     
  19. afterburner

    afterburner F1 Rookie
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    Albert, that would explain things and is easy enough to test.
     
  20. Albert Penello

    Albert Penello Karting

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    Hit me! I'll go out and test it right now :)
     
  21. theunissenguido

    theunissenguido Formula 3
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    I know you mentioned this before but :
    Did you see this picture of it : relais c and m are the brown ones and n the purple.
    and in Urs drawing ;


    [​IMG]




    Means c and d should be Sipea 0442 and n should be Sipea 0440.
    Not like your reply in #15. Is it possible there is the error.

    Guido
     
  22. Albert Penello

    Albert Penello Karting

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    The factory manual is wrong and Urs is correct.
     
  23. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    One thing that might let you know if the pushbutton system is the problem:

    If you push the A/C button with the key "on", and your test light at the heater valve stays "on", and the interior fan doesn't blow = strong sign that the A/C pushbutton system isn't working.

    If you push the A/C button with the key "on", and your test light at the heater valve stays "on", and the interior fan does blow air = witchcraft! ;)

    (If you push the A/E or DEF button with the key "on", your test light at the heater valve should go "off", and the interior fan should blow air based on your prior reports.)
     
  24. Albert Penello

    Albert Penello Karting

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    Aw man you gotta be kidding me. Yes, this is exactly what happens. A/C button ON = Light stays ON and Fan goes OFF. This is a stinker.

    So it looks like A/E and DEF function per spec, but A/C button isn't working. Now I need to sort this out.

    Does this behavior make any difference with the HVAC relay out of the car?
     
  25. afterburner

    afterburner F1 Rookie
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    ... I would test on the unit.... not second-guess. There is only 1 switch inside. It's either off in OFF or on in any other position.
     

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