406 air con intermittant fault

[patrickgledhill]

Hi Guys, i have a 406 hdi 2000 and the air con is playing up. the car was parked up for three months and now it has this fault. The air con sometimes works but not very often. Most of the time there is nothing. Usually with air conditioning i would assume a re-gas it the solution but because issue this comes and goes i'm not at all sure where to look.
I will plug pp2000 in tonight and see if that brings anything up.
any help would be awesome

cheers guys

[spider]

You could try Planet to see if anything is amiss with it I guess.

What is it actually doing ? Can you hear the compressor click in ? Is it a problem with the climate control temperature panel (if you have one)

[addo]

First question is always: Does the blower fan operate at whatever speed setting you choose?

If yes, then there is an AC system issue. Jump the compressor and check it has gas. If it chills enough to frost the low pressure pipes, then check your mixture flap motors.

If no fan, then that is your likely problem. Check at the fan connections for 12V with motor running, if you have this, make the ground connection with heavy gauge wire and check the AC operates now. First item to replace normally is the blower control module common across many Peugeot/Citroën from about '91-02; they range from $25 to $140 depending on quality and source. EAI stock them usually but theirs are not the cheapest. I would not fit secondhand except to test.

[patrickgledhill]

Hi guys, on the off chance the aircon works its only when the compressor clicks in. no click when its not working

all the fan works well through all the levels manually and the auto seems do be ok to. so its not the fans

can there be a period where the pressure switch is indecisive? i will cross it tomorrow

also im not sure what you mean by mixture flap motors?

cheers

[addo]

That does sound like low gas. It shouldn't leak much; mine held factory pressure decently until middle of last year when I cracked it open to remove the heater box and clean it all.

Often an O-ring is pinched in hasty servicing and that is the cause of leakages.

[patrickgledhill]

Cheers, when you say about the hasty servicing, is that servicing on the aircon?
i tried to find the pressure switch to cross it but i cant for the life of me figure out where it is.

PP2000 had the same fault logged in both the aircon and instrument panel ecus: "no communication on the data wire" - would this be related at all?

cheers

[addo]

Your pressostat is usually on or near the receiver drier - follow the aircon lines. It's got a maroon four pin plug on.

You need the motor running to get comms with the climate control module in many cars - was this your problem (engine off)? Otherwise try firmly wiggling the diagnostic plug while pushing it hard into the socket.

Yes, I was referring to people swapping TX valves without due care; that sort of thing. My 605 has lost nearly all its charge in 18 months - not impressed, especially for a car serviced by "specialists".

[patrickgledhill]

cheers Addo, i will check that out tonight. Sorry about the late replys

[patrickgledhill]

Ok i have found the pressostat with 4 wires. do you know what one is the + feed and what one is the connection to the clutch. my multimeter is stuffed so ill get one tomorrow

[addo]

I can't be 100% certain but:

The Bitron box (if you have one) supplies 12V infeed to the black AC relay. It also controls this relay.

Terminal 1 receives 12V supplied by the black AC relay (N/C arrangement) outfeed
Terminal 2 supplies the violet AC relay (N/C arrangement) infeed with 12V subject to acceptable system pressure (normal or slightly low)
Terminal 3 receives 12V switched by the ignition
Terminal 4 sends 12V to the Bitron unit in "normal" and "too high" conditions.

The pressostat has essentially two pairs of contacts - 1&2 etc

It has four positions sensed by each moving contact - nil, low, normal and high pressures. To the best of my knowledge the high and low pressures stated on the side of it are the tip-over and drop-off pressures (ie; the range within which it should be switching normally).

[patrickgledhill]

Ok so measured the voltage on the plug (its grey on mine and attached to the side of the radiator, cant see any dryer anywhere which is weird.)
just to note the aircon was working before i did these tests, first time this week....

with the aircon turned on,
terminal 1 - 12v nothing on the others

with the a/c off no voltage on any wires, if i cross the 1 and 2 terminals will that trigger the clutch? i will have to wait for it to stop working again.
There is a small red box next to the ecu is that the Bitron box?

Cheers

[addo]

Your car has the integrated drier cartridge, accessed by removing a threaded plug on the left side of the condenser unit. It also has no Bitron box, fan speed being controlled by the BSI and underbonnet slave/relay panel. You can simply jump 12V to the compressor to test it.

[patrickgledhill]

Cheers, im a bit confused her as to where to look now for a fault. I no that the compressor works well becasue i have had it working so i suppose the next thing to check is the pressure in the system. does the compressor get its signal directally from the pressostat? and would low pressure still produce nice cold air? i suppose another thing could be the pressostat.

[patrickgledhill]

HI Again, ive done some more research. alot of people have found their fault to be in the bsi. I read that there is a solenoid in the bsi that should click when the air con button is pushed, this is not happening. has anyone else heard of the bsi being the cause of issues with the aircon? it seems a very complex setup compared to the old days of aircon..

[addo]

BSI?

Most of the heavy current is slaved by the underbonnet panel (which is not the BSI). It's worth following the wiring harness back a little to see where it heads, maybe even picking open the slave unit if you're game.