Xantia A/C

Post your Cit/Peu/Ren air conditioning queries or advice.

Moderator: RichardW

User avatar
xantia_v6
Forum Admin Team
Posts: 6712
Joined: 09 Nov 2005, 23:03
x 326

Re: Xantia A/C

Post by xantia_v6 » 15 Oct 2019, 22:09

I was wrong about the fan control. The cars with HDI engines don't have a Bitron fan controller, the cooling fan relays are controlled by the engine ECU (1320 or 12-- in the diagrams), which gets its temperature signal from the blue sender which in this case has 2 outputs, one for the gauge and one for the ECU.

But... The engine ECU also appears on the A/C page, and controls the A/C compressor relay, so the compressor won't engage if the engine ECU is unhappy about anything.

To see how this fits together, you probably need to also see the engine ECU diagram and maybe the temperature gauge diagram...

If you have a lexia, the live data from the engine ECU should tell you something about the state of the cooling fans and the A/C compressor status.

User avatar
white exec
Moderating Team
Posts: 4672
Joined: 21 Dec 2015, 13:46
x 629

Re: Xantia A/C

Post by white exec » 15 Oct 2019, 22:20

I can post these other circuit pages that Mike refers to, if needed.

admiral51
donor 2019
Posts: 1624
Joined: 24 May 2007, 10:11
x 95

Re: Xantia A/C

Post by admiral51 » 15 Oct 2019, 22:46

Guys thank you so much for your replies, it is kinda making sense.
I do need to inspect the connection to the compressor to see if it is connected, guess that really is what i should have done first before posting.:(
Silly thought i have is that both the A/C over heating settings for how the fans operate and the general engine over heating settings for the fans will be the same, why over complicate things, from memory on the MK1 Xantia pulling the stat plug would make the fans operate both together on slow for 5-10 secs or so then they would both go full chat, the same thing would happen if you did the bridge trick with the 2 thin wires on the dryer switch.
My nagging doubt is that on the MK2 some one posted that only 1 of the fans kick in on slow until a certain temp is reached when both then go full chat, different from the MK1 but they did the same thing, pulled the Blue stat plug and bridged the dryer switch and both times the fans did the same thing, both fans worked but not like the MK1.
Chris if you can post those diagrams it will help me but i cannot do much until the weekend in testing but will give me something to work on

User avatar
white exec
Moderating Team
Posts: 4672
Joined: 21 Dec 2015, 13:46
x 629

Re: Xantia A/C

Post by white exec » 15 Oct 2019, 23:22

Will do.

User avatar
xantia_v6
Forum Admin Team
Posts: 6712
Joined: 09 Nov 2005, 23:03
x 326

Re: Xantia A/C

Post by xantia_v6 » 16 Oct 2019, 06:46

The fans on your car should never run individually.
You can see this on the diagram that Chris has already posted.
The relays connect them so that they are always both connected, either in series or parallel.
You may find that using Lexia (engine ECU), you can perform an actuation test for the fans at each speed for testing.

User avatar
white exec
Moderating Team
Posts: 4672
Joined: 21 Dec 2015, 13:46
x 629

Re: Xantia A/C

Post by white exec » 16 Oct 2019, 07:55

Herewith the Engine ECU diagram.
It also shows the coolant temp sensor #1220, which (as Mike says) feeds both ECU and Gauge from its two outputs.
Xantia EWD (RHD) Sep.1998 RP8001- DW10ATED (RHZ)_1.jpg
Xantia EWD (RHD) Sep.1998 RP8001- DW10ATED (RHZ)_2.jpg
Xantia EWD (RHD) Sep.1998 RP8001- DW10ATED (RHZ)_3.jpg

admiral51
donor 2019
Posts: 1624
Joined: 24 May 2007, 10:11
x 95

Re: Xantia A/C

Post by admiral51 » 16 Oct 2019, 19:24

Mike,Chris thanks for that, really appreciate all the help.
So far you have confirmed and disproved a lot of things.
MK1 and MK2 have the same relay set up and the fans must work together, if 1 spins the other should also. My MK2 memory of a 1 fan only working disproved.
MK1 use a Bitron and MK2 use Engine ECU and A/C ECU with input from the Stat plug, MK1 Brown, MK2 Blue ( HDI ) Proved
Both use the same HP/LP switch to talk to Bitron/ECU Proved ?
Only from personal experience having owned both with A/C MK1 and MK2 regardless of fans working under normal operating circumstances when bridging the HP/LP switch with engine running and internal fan on and A/C switch engaged the A/C clutch should be energised and engage, this i have done so i know it works.
Before i delve into the relay triangle and see if the other fan works or not by putting direct supply to it i need to check the supply to the A/C compressor as without power the bridge trick will never work.
Bit of a ramble reply post but just trying to get a to do list together and an order to do it in.
Thanks again for the help

User avatar
xantia_v6
Forum Admin Team
Posts: 6712
Joined: 09 Nov 2005, 23:03
x 326

Re: Xantia A/C

Post by xantia_v6 » 16 Oct 2019, 19:36

One thing that you need to get your head around is that the coil of the compressor control relay (8005) is grounded via the engine ECU, so bridging the pressure switch will not engage the compressor if the engine ECU has a reason to disable it. The reasons could include a stored fault code, such as a cooling fan fault, so it is important to at least read the engine ECU with Lexia, and preferably fix any issues with the cooling fans..

admiral51
donor 2019
Posts: 1624
Joined: 24 May 2007, 10:11
x 95

Re: Xantia A/C

Post by admiral51 » 16 Oct 2019, 19:40

Thanks Mike i will get the Lexia on it over the weekend and delve into it, last time i had the Lexia on it i had no faults at all, only issue i had was trying to talk to the A/C ECU but still a novice on the Lexia but getting better so more confident of delving into live data and ECU etc

admiral51
donor 2019
Posts: 1624
Joined: 24 May 2007, 10:11
x 95

Re: Xantia A/C

Post by admiral51 » 20 Oct 2019, 16:06

Been very busy this weekend taking son and heir out and about looking for a new car, so no progress yet but not forgotten just need to find some time.

User avatar
mickthemaverick
donor 2019
Posts: 867
Joined: 11 May 2019, 17:56
x 254

Re: Xantia A/C

Post by mickthemaverick » 20 Oct 2019, 16:10

Pop down the magistrates court, they're usually happy to give you time! :-D

admiral51
donor 2019
Posts: 1624
Joined: 24 May 2007, 10:11
x 95

Re: Xantia A/C

Post by admiral51 » 20 Oct 2019, 16:26

Thought about that, even a divorce but then i would have the time and SWMBO would have the Xantia, not gonna happen :)