Car Heating

[C2NSX]

Ahhh didnt know the motor doors shut will prevent the heat coming through. When i press mode it changes to window and face but not feet.

The air mix motor controls the water valve i opened moves freely but not getting a signal to open. Guessing if this doesnt open the bottom door no hot air will come through?

[Kaz-kzukNA1]

I think you got bit confused with some of the motor operation.

There are 4 motor driver ICs on the CCU.
Mode, Vent, Air Mix and the Fresh/Recirc.

Mode and Vent motors will select one of the six air outlet modes but you already mentioned that you can’t select the feet (floor) air outlet controlled by the Mode motor so I’ll leave this for now.

Fresh/Recirc motor is as it says. It will open/close the shutter door mounted on the blower motor housing to let the ‘fresh’ air from outside or ‘recirculate’ the cabin air by the means of blower motor fan into/inside the cabin.

The Air Mix motor does control not only the water valve but also the position of the heater damper/doors and this will decide the air temperature blown into the cabin.


This is the reason why asked you the question in my last post when you removed and re-installed the air mix motor assy.
This is nothing to do with the Mode motor that you triggered the error indicator in the Self Diag test.

Strange that it didn’t trigger the Air Mix motor error as well unless the CCU IC didn’t send out the open command when at max temperature setting test.

From what you wrote so far, neither the water valve control nor the heater damper/doors were working and on top of this, you seem to have Mode motor related issue that can’t select the floor air outlet.

As you were saying that the CCU board was tested fine, sounds like someone worked inside the cabin in the past and may be disconnected wiring connectors or placed extra wires/objects that jammed the gear/linkage movement although the heater damper/door linkage is inside the heater unit and only behind the air mix motor unit so not easy to obstruct it...


Kaz

[britlude]

for reference, the air-mix doors are buried inside the heater unit....

[C2NSX]

Thanks both of you, makes total sense now. There was an old phone installed right below the air mix motor control so not sure if this is whats caused some issue in the past.

Kaz if the CCU is causing the issue is this something you can test for? Just so i can be 100% sure

[C2NSX]

From looking the air mix motor looks okay but is no movement from this if i adjust the temperature from the CCU.

[Kaz-kzukNA1]

Thank you for the diagram, Jonathan.

C2NSX, as you managed to remove the air mix motor unit previously, if you have small enough finger like me, you can open as well as close the heater damper/doors by rotating the centre shaft that you can see in Jonathan's diagram.
You can access it at the bottom of the heater unit where the air mix motor is fixed. Obviously, you need to remove the air mix motor again.
There is cross shaped cut out on the motor where you insert the centre shaft. I'll try to take a photo later as I need to remove the floor carpet for one owner any way.

As mentioned above, I don't think you can obstruct the operation there so may be you have electrical wire damage???

In the past, I know one owner didn't push in far enough one of the green connector at the back of the CCU and this caused intermittent connection on a certain circuit resulting in abnormal operation of CCU.
He reported me the issue after I refurbished the CCU board for him but since each CCU boards were tested using my NSX and knowing that everything operated fine, we knew it was something to do on his NSX and thus, he found out the loose connection at the back of the CCU.
You may want to check it as well.

Also, did you try testing the air mix motor as in the workshop manual?
If it doesn't rotate when 12V applied, you found one issue although very unlikely to fail unless something jammed the operation and overloaded the motor.

Kaz

[C2NSX]

Yes know exactly what your talking about turning to open the flaps. Yes 12v applied and the little motor span fine. Part from changing the capacitors and repairing track is there any other components that tend to fail?

For now as being spring/summer soon not a major issue so will continue when i get chance for following through with further testing and if i can find someone local with a good CCU fo try on mine. But will manual open the doors to see if heat does come through.

[Kaz-kzukNA1]

Probably no longer required but for future reference…..

This is the Air Mix motor removed after the CCU settled at temperature setting at 18degC.
Even after you removed the Air Mix motor, you can still achieve the same (if your CCU is operating properly) by reconnecting the electrical connector, set the temperature at 18degC and turn IG key into On position.
Once the cable lever reaches this position, the CCU board tells the motor driver IC to stop the motor so it won't keep spinning and applying excessive force to the heater damper/doors.

This is for the RHD, by the way.

The cross cut out has one narrower channel so you must line it up with the centre shaft of the heater damper/doors.

The Air Mix motor is mounted at the bottom of the Heater unit and in this photo, we are looking down into the upper plane of the motor unit when it's installed at the bottom of the heater unit.

As mentioned previously, if you lie down on the floor facing the ceiling and looking into the bottom side of the Heater unit, you need to turn the centre shaft in clockwise direction as far as possible in order to close the heater damper/doors before installing the Air Mix motor when it’s in the state as per photo. Again, please don't confuse yourself with the direction of the motor as it will be the opposite of the above photo when you are looking up the ceiling.

If you want to test your heater core and if the motor is still working, you could just apply 12V to turn the centre shaft.
If it moved to the opposite direction, just reverse the polarity but make sure to Close the door and set the Air Mix motor to COLD position before re-installing it as you will need to adjust the water valve control cable and you really need to have water valve closed 100% to prevent mild air when you want freezing cold air.

Good luck.

Kaz

[C2NSX]

Thanks Kaz, great help