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12-27-2014, 06:52 PM | #1 |
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Automatic A/C: Ambient sensor airflow?
Hi,
I'm gathering parts to give my HB an automatic A/C, sadly some things are a bit confusing. As I have no service manuals, I have had a look at an EPC drawing which showed an air duct going from the ambient sensor to the upper section of the air box - some cm behind the flaps. However, there's a piece of plastic not closer specified on the drawing which connects duct and air box. As the air box is quite expensive here, I want to get away by simply connecting the sensor and the air box with a small tube, but two questions arise: 1)What is this sensor supposed to measure? If it's the mixed air being about to enter the cabin, it seems legit. If it's the actual cabin air temperature, wouldn't it be better to connect it to a small pc fan or the intake side of the blower? 2)Is that piece of plastic some kind of valve?
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12-27-2014, 07:07 PM | #2 |
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The ambient temp sensor measures the cabin air temp. I believe that the tube simply creates a suction (venturi effect) so that the ambient sensor gets air from the cabin, rather than from the dash.
And, that piece is just a flexible plastic tube. I have also done a couple of the conversions, so I can help if you have any issues.
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12-27-2014, 07:18 PM | #3 | |
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Thanks for your answer
Quote:
It is drawn like a diode, so I would assume that it is a photo diode. Have you made any experiments with usual photo diodes (dark vs. light current etc.) or did you always use the original sensor?
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12-27-2014, 07:58 PM | #4 | |
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Quote:
I checked and do not have one, but the service manual for the Prius (which uses the same sensor) confirms it is a photo diode. The only specs it lists is that the resistance of the photo diode will be an open circuit in dark and not an open circuit in light.
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Last edited by CTScott; 12-27-2014 at 10:07 PM. |
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01-02-2015, 10:00 AM | #5 |
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Now I have got the parts and successfully soldered white LEDs into the control assembly, but I'm already running into problems.
Following the wiring diagram, I thought the servos to have included some LIN electronics or the like, so it could be on a 3 wire bus. Instead, each one has 5 pins, 3 of them lead to some kind of rotary encoder and the other ones lead directly to the motor. Before I start analyzing the PCB: Do you have any hints to which pins these servos connect to? Sadly, I was not able to get the connectors or even a wiring harness.
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01-02-2015, 10:58 PM | #6 | |
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Quote:
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01-04-2015, 02:06 PM | #7 |
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I have had a look at some drawings and have come to the conclusion that the servo controllers are a part of the rather small servo harness.
I am not a 100% sure, but it seems to cost about 160€. That's a lot, however, the alternative would be building 3 servo controllers which would be cost effective, but take a bunch of weeks. The even bigger problem is, the 4800 baud serial data on the bus pin does not change as I e.g. change where the air goes out according to the display. Possibly, this is because the A/C is missing the other devices on the can bus, but the weather ATM is too cold for me to spend some hours outside in my car, so I hesitate to pull the original A/Cs fuses and hook it up to the bus. Techstream requires the ECU to be present on the bus, so I can not do anything with it up to now. My automatic A/C came from a european TS which is almost entirely JDM and has an air ionizer which I did not find on any wiring diagram - did you have any mysterious wires on the connectors you bought?
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I drive, therefore I am. Last edited by dj92; 01-04-2015 at 05:41 PM. |
01-04-2015, 09:08 PM | #8 | |
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Quote:
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01-05-2015, 07:43 PM | #9 |
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I poked into it with Techstream and found out that it in fact misses the servo controllers - this single-wire bus is bi-directional.
You don't have only the harness with the controllers inside to sell, do you?
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01-09-2015, 03:53 PM | #10 |
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This was posted in the wrong section of the forum, moved it to the correct one.
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