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ALLSPEED

Hvac Controls To Monitor Engine?

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I have a 99 996 C2 6spd and searched but didn't find this. Did I understand someone saying you could monitor engine temp. from the HVAC controls? If so, teach me please.

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Try this.... I bet you gonna try this the first thing you wake up!

Porsche AC Diagnostics

(undocumented, unsupported feature)

The AC Climatronic unit is actually manufactured by Audi. There is some sort of serial data stream (not CAN) that allows the AC unit to display engine parameters. This works on 1997-2000 boxsters. Same as 996....

To switch from F to C:

Hold down the recirculating button then push both the temperature + - buttons.

To access diagnostics:

Hold down the Recirculating & Air up buttons for 5 seconds. The + - buttons go up and down through the list of "c" codes. The center vent button switches the left display between the "c" code and its actual value. Press the Auto button to exit.

I have yet to verify all these, this info was copied from wonderful people on PPBB!

Here is a list of what can be seen:

0c - ERL

1c - Oil Temp?

2c - Inside temp. Sensor mounted in the aspirator assembly at the side of the dash.

3c - Outside temp. Sensor located inside the air inlet of the A/C unit.

4c - Outside temp. Sensor located in front grill of the radiator. The data is fed to the Climatronic from the instrument cluster. When not moving, the instrument cluster OBC temp display retains it's last setting until moving. This is to prevent heat emanating from the radiator affecting the temperature sensor. The A/C unit uses the lower of the two outside air temp values in determining fresh-air temp.

5c - Outside temp. (matches OBC outside temp display)

6c - Coolant temp.

7c - Footwell discharge temp.

8c - Sun sensor (dash top)

9c - Sun sensor.

10c - Passenger compartment fan speed.

11c - Passenger compartment fan voltage.

12c - Temperature mix Flap command 1=COLD, 100=HOT

13c - Temperature mix Flap position

14c - Central Flap command

15c - Central Flap position

16c - Footwell/Defrost Flap command

17c - Footwell/Defrost Flap position

18c - Recirculation Valve command 1=OFF, 100=RECIRC

19c - Recirculation Valve position (feedback)

20c - Vehicle speed in kph, updating only once per second. (real speed, not speed+safety margin as in the speedometer)

21c - Engine RPM in hundreds. This too only updates once per second.

22c - ?

23c - ?

24c - Sun sensor, exterior lights switch & panel lights control (term. 58 & 58d voltage) - used for A/C panel display illum.

25c - ?

26c - ?

27c - ?

28c - Fan speed?

29c - ?

30c - Engine run time in seconds (255 max.)(=0xff)

31c - Timing counter

32c - Displays test

33c - Software version? Mine states 3.4

34c - ?

35c - Outside temp. from inlet sensor (filtered?)

36c - temp?

Edited by Rob001
  • Upvote 1

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Couldn't wait till morn. Needed to park car anyway. Speedo reads 2.5 mph faster than actual. Less than I thought. Engine coolant gauge reads 10 to 12 degrees cooler than actual. Bummer! This is awesome. Thanks again Rob. Robert

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Hahaha I thought so, glad it works as I could not yet try myself as I'm somewhere in Siberia for the moment.

Rob

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any one j iw if there is a similar function for mkii 996s?

Thanks

No there is not. Both the Climatronic and cluster changed in MY02. All signals are now on CAN at that point.

The HVAC temps, flap positions etc are through HVAC sensors - all engine readings come from the instrument cluster.

If you hook up the Durametric software, a PST2 or PIWIS tester you get these and many many more.

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It's been a long time since I've used those controls but I don't remember them being accurate compared with what the actual ECU is reporting.

That, and I think all of the temp values were reporting the same thing.

Next time I'm able to and remember I can try to compare those values.

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1c is not oil temperature. You can't read it through the AC panel. The 'climate diagnostics' only work up to about 1999. It definitely doesn't work on the 996-2.

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Does a more complete list of the "AC diagnostics" exist? In particular, I am interested in the engine compartment temperature reading, but other parameters could also be useful.

 

Thanks 

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16 hours ago, Philip54 said:

Does a more complete list of the "AC diagnostics" exist? In particular, I am interested in the engine compartment temperature reading, but other parameters could also be useful.

 

Thanks 

Get a cheap Bluetooth or WiFi ODB-II reader and an app on your phone like DashCommand or Torque. They can display the engine compartment temps and much more in real-time. I have the iCar II from Vgate. I think it was about $30, which is more than some. What I like about it is that it turns on and off automatically so you can leave it plugged in without worrying about draining your battery. I have the WiFi version which works with iPhone. The bluetooth version works with Android. I'm not sure if those restrictions still apply. I have the DashCommand app but a lot of people like Torque.

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On ‎5‎/‎20‎/‎2020 at 8:37 PM, wyovino said:

Get a cheap Bluetooth or WiFi ODB-II reader and an app on your phone like DashCommand or Torque. They can display the engine compartment temps and much more in real-time. I have the iCar II from Vgate. I think it was about $30, which is more than some. What I like about it is that it turns on and off automatically so you can leave it plugged in without worrying about draining your battery. I have the WiFi version which works with iPhone. The bluetooth version works with Android. I'm not sure if those restrictions still apply. I have the DashCommand app but a lot of people like Torque.

Thanks for the information.  These tools and applications could be useful also for my other car.

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