Automatic A/C: Ambient sensor airflow?

[dj92]

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?

[CTScott]

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.

[dj92]

Thanks for your answer

Originally Posted by CTScott

I have also done a couple of the conversions, so I can help if you have any issues.

OK, another issue is the solar sensor - also pretty expensive here (80€ or so) and hard to get, so I feel tempted to test my electronic skills
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?

[CTScott]

Originally Posted by dj92

Thanks for your answer



OK, another issue is the solar sensor - also pretty expensive here (80€ or so) and hard to get, so I feel tempted to test my electronic skills
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?

The OEM sensors are used on many other Toyotas, so they can be found inexpensively. They are just photo diodes, but I didn't test the characteristics. I may have on hand. If I do I will check it out shortly.

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.

[dj92]

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.

[CTScott]

Originally Posted by dj92

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.

I have always gotten them with the harness between the servos and the ECU, so I have never had to worry about that pinout. Let me see what I can find, as the service manual does not even show that info.