Air Con Compressor Not Kicking In

[OrgoneAccumulator]

Hello everyone,
Newbie to car forums so put me straight if I err!

My car spec is:-
406 STDT 2.0 HDi 110BHP
8BRHZE
DW10ATED
RHZ
1996cc
BOSCH EDC 15C2
ML 5 T - 5 Speed Manual
It's had a sheltered life only 100k miles and well maintained.

Problem History:
At first the air con would pack in after half an hour ONLY when weather VERY hot but run fine later on the same day when cooler.
If moderately warm weather it would run fine all the time however of late (2weeks) it would click in then drop out over ever decreasing periods after starting the engine.
Now the clutch refuses to kick in at all when air con button pressed and I start the engine.
My air con specialist garage recently diagnosed gas level is ok, the pressure switch is not defective and the fan (single I think) comes on when the aircon button is pressed.

I am an experienced electronics engineer so I intend to fix the electrical problem myself even if I have to solder my BSI !!

What I need some help with is :-
1) locating a full circuit diagram for my Pug
2) some pointers to the likely culprits ie. the 3 fan relays, fuses, Aircon ECU (8080) or anything else as a likely cause...

Many thanks in advance for your replies )
Org

[Welly]

Are you totally sure the gas level is ok because the symptoms you describe perfectly match a system low on gas - even down to it sometimes working, sometimes not - this is a phenomenon of refrigerant gas in changing ambient conditions.

The favourite culprit is the condenser up front - look for an oily, green-ish staining at the bottom part.

[plod]

I'm not clued up on aircon, but could it be the temperature sensor within the cabin playing up
Again, not clued up, but it's not the one by the interior light switch is it guys that gets crudded up is it?

[Doggy]

Hi Org & welcome to the forum.

I appreciate you have provided comprehensive details of your car, but unless I missed it, the age of the vehicle is not stated?

If it is new enough, this link (http://www.petrila.net/pug/Service/index.htm ), should help with circuit diagrams.

[OrgoneAccumulator]

Hiya Welly,
Thanks for your response

Are you totally sure the gas level is ok because the symptoms you describe perfectly match a system low on gas - even down to it sometimes working, sometimes not - this is a phenomenon of refrigerant gas in changing ambient conditions.

I had the condenser replaced about 12 months ago after a leak - the same garage did that...
Over the last 2 weeks the number of times the AC clicked in has decreased quickly - if it was refrigerant leak I would have thought my garage would have spotted it...
He checked for leaks using his UV light n glasses and seemed satisfied there was enough gas in to run the compressor.
Maybe there is a volts test I can do on the High/Med/Low pressure switch to verify the gas pressure?
Cheers

[OrgoneAccumulator]

Hiya Plod,
With a name like yours I must first assure you all my documents are original, up to date and fully available on request!!!!

I will have a look at the sensor and clean it - do you just prise the grey surround plastic away from the roof?

Thanks for your reply
Org

[OrgoneAccumulator]

Hiya DogsLife,
Thanks for your welcome
The car was first registered in Dec 1999 - I just hope I didn't get the one with a millenium bug in the firmware!!!
Thanks for the link - just what I need - nice one!
It probably is a numpty question but the 'build code' is in the 8 numeric digits at the end of my VIN?
These numbers are 80994427 - is my 'build code' after 9001 as indicated by the group 80 diagrams on the website at your link?
Again many thanks in advance...
Org

[Doggy]

No, the build code is on the sticker on the drivers doorpost that gives the tyre pressures etc. Towards the bottom, there's a series of numbers etc, mine looks like this:

0947189
20159
EYLC**
5573

You use the 2nd through to 5th characters, in the top number, for example mine is 9471

I suspect your car will be before build code 9000, which means the link I posted may not help. In this case the diagram in the Haynes 406 manual 1999 - 2002, is probably applicable. (I have a copy if you have specific question).

[OrgoneAccumulator]

Hiya Dogslife,

Thanks for that, my build code is 8431 as you suspected...
I guess that I do not have a CAN bus on my car then making the drawings at your link non applicable?

About the Haynes manual you mentioned - I guess you cannot scan the page for fear of copyright enfringement?

One question I did have is that when I switch on the AC button there is no click from the BSI relay (unless it's very quiet), no click-in of the clutch (as reported) and the engine revs do not lift slightly as expected...
...does the signal for the engine ECU for the revs come from the BSI, the BSI clutch relay, the aircon ECU or some other means?

If it comes from the BSI relay then I will pursue a relay replacement but if it comes from the BSI or AC ECU then why doesn't it tweak the revs?
The lack of responses I experience when I press the AC button is ominous considering there is gas in the system and the pressure switch swap-out makes no difference!
Maybe the BSI or AC ECU does not see a rise in coolant pressure therefore leaves the revs alone?

Thanks in advance
Org

[Doggy]

I've check Haynes - unfortunately it doesn't have the a/c on any of the diagrams, sorry I thought it would be there.

Think I saw a link to some earlier diagrams on peugeotcentral, but can't find it at the moment.....

[OrgoneAccumulator]

Cheers DogsLife,

I took the BSI out last night - it is a Seimens.

Before I removed it I heard a click from it when I pressed the aircon button on - encourage by that I broke the feed to the compressor and measured the volts from the BSI - they seems to dance around between 4 and 10v !!

I guess there is a possibility there is a broken wire but my money is on the relay contacts gone soft - do you agree?

I have a JSM1-12v-5 relay arriving today from Farnell will fit that and see if the feed volts improve...

Watch this space!
Org

[Doggy]

my money is on the relay contacts gone soft - do you agree?

Sounds, like a safe bet.

Post a picture or two of the swap if you can, (it's only a matter of time until I have to do mine)!

These days, I don't know I trust my eyesight to try to unsolder it from the board, I may just butcher the old one, attach some flying leads to the remains & mount another relay externally, preferably in a socket......

[steve_earwig]

I'd be a bit cautious about just replacing it with a standard automotive relay 'cos the values on it (current etc.) would be different - remember what happened to Farmer P!

[OrgoneAccumulator]

Hiya DogsLife,

Today is a good day for Air Con in my car - the relay replacement in the BSI fixed the problem - hoorah!

Pity I couldn't fix the weather as well - this August we don't need air con lol

I didn't take any pictures except one on my phone to remind me where the BSI connectors went.

Access to the BSI is easy:-
- drop the rake adjust lever under the steering wheel
- undo the 3 lock pins and remove 2 TOK screws to free the relay cover panel.
- Remove the brass spring clip holding the BSI against the lugs at the front of the BSI tray
- wiggle the BSI out being careful not to snag wires on connectors
- remove all the connectors from the BSI (as an electronics engineer I have NEVER seen such a weird array or over engineered connector types!!! The French eh? )

From then on I followed this guide for the Siemens BSI:-
http://bratene.net/?p=86

I used a dremel router bit to remove the vented cover area but covered all the connectors with masking tape to prevent swarf caking them up. (some are primed with silicone grease)
The de-soldering is only 5 pins but they are medium gauge pins with one onto a ground plane so heat with a little primer solder wait 4 or 5 secs then soldersuck - be sure the pins wiggle freely in their holes before pulling anything off the PCB!!!!!
If any pin 'sticks' to the side of the PCB hole then apply a dry iron tip to the pin ONLY and and apply SLIGHT pressure to move it away from the stuck area - if this does not free the pin then repeat the primer solder above again...
Do not repeat the primer / suck any more than 3 times as there is a danger the heat will damage the PCB - call for help!

Your idea to break up the relay and attach flying leads will work but you still have to remove the vented area - do be careful not to get relay shrapnel into the BSI!!

Thanks for your help with this matter and if you or any of your mates want any soldering advice etc etc then send me a PM?

Cheers
Org
(one happy bunny)

[OrgoneAccumulator]

Hiya Steve_Earwig,

Thanks for your warning.

The contact rating of the JSM1-12V-5 relay I used is 15A.

Trolling through every website that has stooped low enough to divulge the current rating of a compressor clutch coil I can see that they typically take 5A or less.

I think my relay is man enough?

Who's Farmer P by the way?

Cheers
Org