zmaj

soooo, i went into the hvac unit -> read data stream —> sensors and there i found the sensors. You have two sensors per side, also in the middle airoutlet (next to the pcm) they have potentiometers which is also under the sensor section

tarasok

I checked internal sensors, looks like they work as expected.
I tried to lubricate mechanical parts for recirculation motor (see image), I wanted to get rid of plastic cover, but didn't have time to unscrew. It is very interesting mechanism, looks like it not only regulate recirculation flap, but smth else... I lubricated everything and checked by hand to move flaps, looks like after lubrication it worked fine... but again, I see mechanical error even I unscrewed and pulled out motor....
I can clear error code, but it appeared again after some time.... probably, need to somehow configure servomotor and mechanism in right position....

tarasok

Today I played with Thinkdiag and tried to reproduced recirculation flap issue...
First, it reproduced quickly when I turned off/on hvac.... then I did some tests moved to 0% then to 100%... issue is gone.... and later appeared randomly....
I also read downstream from flap, when it is open - 33.2% when closed - 0%. When driving - it may vary 20-30%...
Still have no idea why it happens...

I also read interior temperature sensors and looks like 4 sensors are fine, but one has invalid value, it is "Temperature downstream of heat exchanger", if it is broken, it might be main issue cause...
Do you have same in your thinkdiag tool? if no, probably sensor fault... if it is fault, need to find where it is located.

zmaj

hi, I have an app caled diagzone (obd head is from launch)
will do tomorow a screenshot what my readings are. In thw fro
nt left footwell I had a reading of 85c
today came my new sensor.

let you know tomorow

zmaj

hi,

here are pictures of my sensor readings

tarasok

Thanks zmaj for reply, Looks like you don't have Temperature downstream of heat exchanger in your screens, so probably it is an issue in my Thinkdiag tool
That's bad news for me, because now I have no idea what cause strange hvac behavior and recirculation flap motor issue...

tarasok

So, I think it might be faulty middle airoutlet sensor, but I don't see its temperature in tool and not sure if it really exists..

Tim Matar

Hi CAVU, this documentation you posted is quite helpful so thank you for sharing. I am trying to troubleshoot an overcooling issue in my 2011 CS which requires me to understand the operation of the cooling system, especially the more complex operation of the Thermostat (TSTAT).

I was aware the 958 had a MAP controlled thermostat but I understood it was all about being able to open the TSTAT faster than coolant temp would otherwise allow, I did not realise (or I cannot understand) how it can also supress coolant and increase temp. The article makes several references which imply this. I would like to know your interpretation is the same or if I have misunderstood this. As follows:

'Map-controlled coolant temperature regulation by supressing coolant flow during the warm up phase.'

'The thermostat permits automatic, demand-based suppression of the coolant flow when the engine is cold (cold start).'

I also didn't realise the 'small circuit' or 'bypass' (I believe they are the same) required some opening of the TSTAT which would require DME intervention due to coolant temps on a cold engine.

'Electrical pre-heating makes it possible to quickly open the bypass for the smaller engine circuit in a controlled manner during the warm-up phase.'