C3 1.4 Hdi Heater/AC not working

[philou4130]

Hi everybody,

Writing from Belgium, with my school english learned 40/50 years ago.
I have a C3, 1.4 hdi 11/2011 SC8HR4 motor 8H01.
I had problem with AC in the summer 2020.
AirCo was recharged without result. The little garage proposed to change the compressor and we were still in the problems.
After a lot of hours of search the airco began running. But only for a few weeks.
I was disappointed and quite ready to go and find a specialist to solve the problem. But I did nothing ant stayed with the breakdown.
In september 21, driving from Belgium to the mediterranean sea, arriving in Menton after 1200 kms, waiting the green light at a crossroad, Airco surprised me beginning running. And it was so for the hollidays with some little stops and sometimes a few minutes were necessary before it freezed.
We did not use airco during the winter's months and it's no more possible to receive any fresh air since that time.
I have a rendez-vous the 1st september to solve the problem. The mechanic is not an official Citroën but specialized in this brand. Years ago he sailed Citroen cars but times have changed....
He said me that if I had the official electrical diagram, he was sure to solve the problem , as he is experienced with electricity.
So I bought the official "revue technique automobile" of the C3 II but my model/motor was not in this one.
Looking on the net, i found another one concerning the SC8HR and I bought it again.
In the first ihad three different diagrams : a schematic diagram, a cable schematic and a position diagram. (Google translate)
But in the second one I have only the schematic diagram. And i would be interested to have the other ones at his disposal.
I'm not sure it is necessary for him to find the problem but I think the more information I have, more easy it should be to solve the problem.

Thank you for reading this post. Thank you if you can send me those two diagrams if you possess them.
I saw some concerning airco in different topics of the forum, so I try my luck.

Have a nice day.

Best regards.

Philou4130

[GiveMeABreak]

Hi.

If you can post up your VIN located on the lower corner of the outside windscreen, I should be able to put up the diagrams for the A/C circuit for you.

[philou4130]

Hi Mark,

Thanks a lot for your quick reply.
I saw you regularly contribute to the different topics. You are a Pro !!!
Here's my VIN : VF7**************[VIN obfuscated, can be read by forum staff]

Thanks again,

Philou 4130

[GiveMeABreak]

These diagrams are specific to your C3 build date and options.

Most of the codes can be found in hierarchical numbered sections on the Wiki:

https://frenchcarforum.co.uk/wiki/Elect ... ring_Codes

Here are the main Equipment codes:

BCP3 : Relay 3 protection switch unit
1320 : Engine ECU /
8007 : / pressostat
8006 : Evaporator thermistor (if separate)
8030 : Car interior air thermistor
8033 : Sunshine sensor
8080 : Air conditioning ECU
8020 : Air conditioning compressor

[philou4130]

Good evening Mark,

Thank you very much.
I"m gonna print them.
It's interesting to have colors : it's easier to follow the different electrical circuits.
Mine was in black/white.

I'm coming back late : I had booked a restaurant.

I will let you know the result after my visit to the garage.

Have a nice sunday.

Many thanks once more.
Best regards,

Philou4130

[ozvtr]

The title of your post says "heater/AC not working". Does the accessory heater work? You only mentioned problems with the AC.
The compressor was changed?

[xantia_v6]

Another cause of the compressor not engaging is that the engine ECU will disable it if it thinks that there is a danger of the engine overheating. There may be no other external indication of this, you need to read the live data from the engine ECU while the fault is occurring.

[philou4130]

Hi Ozvtr,

Yes, he changed the compressor. Because he found nothing else.
But it didn't solve the problem.
The mechanic had to spend a couple of hours before it runs despite the change. But for only a few weeks.
I'm afraid it wasn't necessary to manage the matter this way.

Hope a new mechanic find the problem thursday.

Philou4130

[philou4130]

Hi Xantia_v6,

Thanks for your remark.
I share it with the mechanic thusday, before he begins to work on the airco.

Regards,

Philou4130

[philou4130]

Hi Marc,

Just to tell you I wonder why I persisted in writing your name with a K

Philou4130

[philou4130]

Hello Marc and everybody,

I caught a cold yesterday lol.
First my mechanic believed the PSF1 part was out. We had voltage in and nothing out.
So we changed it but without result.
Than immediately after he connected the diagnostic socket and the computer, he touched the pressure sensor wires and we heard the "clic" of the compressor
Airco. was working again.
Here is the photo of the sensor

Thank you very much again Marc and the others who gave me advice.
Best regards

Philou4130

[ozvtr]

That's the "high side" pressure sensor. The engine ECU reads it to determine 2 things.
1) If the pressure is too high or too low it wont engage the compressor.
2) The pressure determines how fast the radiator fan runs.
Unfortunately LEXIA does not tell you what pressure is in the AC high side. Only that the compressor operation is enabled or disabled. Not helpful!
So with no signal from the sensor your engine ECU would have read the system as having no pressure and it would not have allowed the compressor to run.