Xantia A/C

[admiral51]

First off vehicle details
1999/2000 2.0 Hdi MK2 current mileage 89262 verified
Vin is in my signature

I have had my fair share of Xantia's and this particular one was bought 11 months ago as a needs must replacement, i knew the marque and i never thought i would get my hands on another one.
I sort of know the relay system for the fans but really only on a MK1 , MK2 seem to have 1 fan running at low speed whilst MK1 had both running in sync and then both going full chat.
Think i have had 5 maybe 6 Xantia's over the years but this is the only one that i cannot get the aircon clutch to engage by doing the HP/LP switch bridge trick.( MK1 and MK2 had both)
TBH i have not yet delved into the wiring to see if the connector has been unplugged from the compressor but did not think i would be allowed to keep it long term ( SWMBO etc lol)
Did i mention it has spent 14 years in Spain so ATM r**t is not a problem
Seriously though any help in the electrical side of the aircon will be much appreciated, i am fully aware i could need a compressor/dryer/rad as i guess it has not been used for many a year,along with multiple seals but the aux belt has not been changed to bypass the aircon compressor so fingers crossed it is an electrical issue.
Have tried to talk to the aircon ECU but Lexia says it cannot communicate but from memory that is nothing unusual.
Thanks in advance
Colin

[xantia_v6]

I hope that Chris can post up the correct schematics for your fans and A/C. The fans should both run at low speed, so you have an issue with those to sort, maybe a seized fan or corroded relay socket.

Do the other heater controls (temperature control flaps, blower speed) seem to work correctly?

[white exec]

Hi Colin,
Will post the circuitry a bit later this morning.

[white exec]

Hi Colin,
Right - back on the case.
Can't pull up your VIN from your Signature: not Moderator-visible there.
Could you just post the VIN for me?
Thanks.

[GiveMeABreak]

It's here Chris, just click on Colin's profile name and it will display for you.

VF7**************[VIN obfuscated, can be read by forum staff]

[white exec]

A/C wiring diagrams for the car
Xantia 2.0 HDi 90 BVM5 DW10 TD RP=8346
click to enlarge

Hope helpful.

[KennyW]

Colin,

Have you checked the 3 relays in the black triangle cover in front of the fans. My xantia had a burnt out relay which stopped them working correctly.
Easy to get to as a starting point. you can start the fans by running small wire bridge between them but don't kept it running for long. Just enough to check the fans work.
I presume you have removed the brown Briton plug to see if both fans run at full speed.

Kenny

[admiral51]

Thanks guys given me more of a headache now as the old grey matter is confused.
The schematics i have saved and will get printed off at work tomorrow thanks for them Chris.
V6 everything works fine with regards to the heater controls goes from cold to hot and back again with no issues and all vent settings are working as they should, even the recirculation works ie inside/outside air flow.
Kenny i have not really investigated the issue yet, although i cut my teeth on the Xantia A/C on a mk1 and followed Clogzz and Alan's posts and got everything sorted.
From memory as SWMBO has the car today i cannot check, but i think i pulled the Blue connector by the filter/stat housing and only 1 fan spun up, same as when i tried the dryer switch bridge.
Somewhere i think i read that the MK2 set up was the same, relays etc but that the fans did not run at the same time, only 1 spins until the temp-A/C pressure gets too high and then both kick in at full chat, before that only 1 kicks in on slow ( normal ) not full chat.
Not happy too but done it before so guess eventually it will boil down to front bumper off
This is the first time i have not been able to get the A/C clutch to engage by doing the dryer switch bridge so got me scratching my head again to try and remember

[white exec]

As the problem looks to be the cooling fans, the diagrams for those are as follows.
Looks to be the classic arrangement of 2 fans plus relays for the DW10...

As Kenny says, with IGN on, unplugging the Brown sensor usually brings fans on at full speed.
Turn them off by re-connecting the sensor, then turning IGN off then on.

Turning on AC should bring fans on at slow speed.

[admiral51]

Okay a quick update now that SWMBO has returned with said car
Too dark to take decent photos and engine a tad warm ( roasty not toasty lol ) but had chance to remove the engine cover and can confirm that the colour of the plug is Blue, and it is what i believe the Stat sensor plug and is directly underneath the air intake pipe from the air filter box to the right of the engine bay as you look from the front bumper into the engine bay.
Something still nags at me that MK2 were different to MK1 in the fans running but cannot remember where on this forum i read it, head say Simon posted something about it but cannot be sure, will need to wait till the weekend to get control of the Xantia to try out the bridge trick to test fans and clutch plus remove the blue plug and see what happens.
Really appreciate the replies just need to get my head upto speed again on the Xantia air con

Colin

[admiral51]

Bugger forgot to say what Kenny and Chris have said is 100% of everything i remember for the MK1 , both fans should run at slow and then both together at full chat,but if the the so called #1 fan does not work/no power etc then the #2 would not spin as it took power from 1 of the relays in the triangle of 3 to power it up when #1 fan started,this is going to give me grief i can just tell

[xantia_v6]

I don't understand why you are talking about the blue sensor plug. It only connects to the temperature gauge in the dashboard. The brown sensor is the one used by the Bitron fan controller.

The only difference that I am aware of in the operation of the A/C system between the late mark 2 and earlier cars (mk1 and early mk2) is that on the late mk2, the A/C is automatically switched on in demist mode.

[admiral51]

Brain is slower than fingers again, think i need to get underneath and check the connection to the compressor to see if i get any power to the plug when i bridge the HP/LP switch on the dryer. Logically if i bridge/bypass the switch then the clutch should engage if internal blower is on,A/C button on ( i do get a green light so power to it ) engine running as all i am doing is ticking all the boxes to start the A/C and the bridge eliminates the HP/LP sensor ?

[admiral51]

Ah V6 you are talking about the 4 wire brown plug on the air dryer ??
2 thick and 2 thin wires, bridge the 2 thin wires and fans go full chat, bridge the 2 thick wires and the air con clutch is engaged?
On the MK1 1.9td there is a brown plug on the stat housing, with the engine running if you unplug it as it sets the fans on full chat as it has no signal and goes to default and assumes it is overheating.
The same should apply on the MK2 Hdi but from memory of posts on here it does not, it only put 1 of the fans on full chat

[white exec]

In the circuit diag above (2 fans, 3 relays, and control by the engine ECU), the temp sensor is #1220. Three-way connector, but only two wires connected into the fan circuit. If BE means 'bleu', then it is indeed blue . . . not the traditional brown.

Can't see any other temp sensing shown. Relays appear to be standard 5-pin 12v 30/40A changeover type, so easily renewed if necessary.

It removing and playing around with the original relays, it's important to get one of them (#1504) in the correct slot, as it is the changeover one. The other two are just makes. If you fit new relays, just use 5-pin changeover for all three, so positioning is immaterial.

Arrangement is classic series (slow speed) parallel (fast speed), and no electronic speed control or dropper resistor, so, as you say, both fans need to be in working order for Slow to operate.

If one is dud and open-circuit, only the good fan will run on Fast; nothing will run on Slow.
If one is dud and shorted/seized, on Fast it will blow its fuse. On Slow, just the working fan will run, Fast.
Both fans should, as you say, always operate at the same speed, and together.