Locating part for air con

Mandrake · Post by **Mandrake** » 18 Feb 2006, 23:59

dnsey wrote:I don't know much about aircon, but I believe that there are sensors which check for overpressure, freezing etc., and which prevent operation under fault conditions. Any of these might be faulty, or indeed doing its job correctly and detecting a problem with the a/c system.

Yep,

It's just a matter of knowing for sure where each sensor is and how it works while trying to work with the minimal amount of service information available

Regards,
Simon

Mandrake · Post by **Mandrake** » 19 Feb 2006, 00:03

alan s wrote:I don't know that the Bi-tron controls the compressor; the fans, yes.
Usually they have a seperate relay controlling the compressor due to the sudden power surge created by snapping a solenoid in, but I also understand that Xantias have an internal fan that circulates ambient temperature across the sensor for the air/con, in which case, an intermittent problem with that would also lead to a problem such as you describe.

Alan S

Hi Alan,

Thanks for the heads up about the small fan behind the dashboard, presumably its a big job to get access to it ?

With the key turned on but the engine not running I can here a small buzzing noise behind the dashboard, could that be a problem ?

I always assumed it was the motor that controls the hot/cold flapper not quite shutting off when set to the cold end of the range, but I'm not so sure now.

As for the relation between the bitron and the air conditioning - the bitron plays a roll in sensing the water temperature and controlling the fan speeds, and I understand it will also disable the air-con clutch if it detects an extreme over temperature problem with the radiator to reduce the heat load on the cooling system.

Regards,
Simon

Mandrake · Post by **Mandrake** » 19 Feb 2006, 00:10

Clogzz wrote:Can't find it now, but read a story of one of the aircon bottles having a 4-wire plug, 2 thick, 2 thin.
With engine stopped, or even with the key out, shorting the 2 thick wires should turn on the compressor clutch, and shorting the 2 thin wires should start the cooling fans at low speed.

Ok, I do seem to have two thick green wires and two thin ones, although I am a bit chicken to go shorting anything out without knowing for sure what I was doing

Regards,
Simon

Mandrake · Post by **Mandrake** » 19 Feb 2006, 00:22

Clogzz wrote:
Mandrake wrote:where the bitron is in my car, or what it looks like.

Thanks for the picture clogzz,

But I wonder if my car is the same ? I'm pretty sure that I can see the area under the headlight from the rear with a torch, and it is empty - there is a bolt sticking up looking like it might be a mounting point, but nothing there.

On the other hand there is a large black box with a plug on it just hanging down in front of the battery with no mounting

It looks very much like the box in your picture... it has a plug with an unusual sliding lock which has a diagonal track in it...

And there is also another box attached to the side of the guard with two plugs. I might have a look today and see if I can make any sense of this, and take some pictures too.

Regards,
Simon

Mandrake · Post by **Mandrake** » 19 Feb 2006, 09:15

I got a chance to have a look at it today, I took out the battery and the mystery box that was hanging down in front of the battery, and it would indeed appear to be the Bitron.

The gap under the headlight was clearly empty when I inspected it through the rear with a torch with the battery removed, so fortunately no need to remove the headlight to confirm that. (Which would involve taking all the bumper etc off as well)

Looks like someone else has been chasing this problem before me, or just got lazy and didn't fit it back in its proper location, the cable length is just right to reach the location under the headlight. I've cleaned the contacts on the socket thoroughly with LPS1 and for good measure I did all the other plugs in the area around the battery as well. (Theres rather a lot of them....I wonder what they all do...)

There was a little bit of white frosting on the inside of the plug which suggests some water has got into the plug at some stage.

For now I've secured it back between the battery and headlight rather than refitting it to its correct location, especially given I don't even know if I've fixed the problem yet.

So far the air-con hasn't misbehaved, but its early days yet. If it can go for a couple of weeks with no failures then I might consider it fixed..... fingers crossed

For people that have had Bitron faults, is it usually just poor contacts that cause problems, or can the unit itself sometimes fail ?

Regards,
Simon

Clogzz · Post by **Clogzz** » 19 Feb 2006, 11:45

Kowalski wrote:Can you actually see that with the bumper on?

Looks like the question has been answered since.
Yes, you can, by removing the battery.
2 pictures, so as not to waste the post.

Clogzz · Post by **Clogzz** » 19 Feb 2006, 13:16

Mandrake wrote:trying to work with the minimal amount of service information available

From the reading-up that I’m doing on ‘planet forum’, there is sensing for many things, including outside temperature.
Peugeot is more use with service information:

http://www.peugeotlogic.com/workshop/ws ... /ac405.htm

the small fan behind the dashboard, presumably its a big job to get access to it ?

The fan can be unclipped from the right, if I remember correctly, and dangled out.
The metal surfaces need silicone where they touch, and that’s cured my noisy fan.

two thick green wires and two thin ones, although I am a bit chicken to go shorting anything out without knowing for sure what I was doing

Lucky you, mine has 5 wires, 4thin, and 1 thick.
This map shows the 4 connecting pins of the pressure switch:

http://www.frenchcarforum.co.uk/forum/v ... hp?t=17012

large black box with a plug with an unusual sliding lock which has a diagonal track in it...

Surprising, I have the sliding lock with diagonal track mounted on the inner wing near the battery, as if it was connecting through to the inside.

didn't fit it back in its proper location, I've cleaned the contacts on the socket thoroughly with LPS1

Good idea to dangle or stick it somewhere accessible.
The pins of my Bitron needed a good scrape.
A previous ordinary clean was only good for a few days.

For people that have had Bitron faults, is it usually just poor contacts that cause problems, or can the unit itself sometimes fail ?

Say that 9 cases out of 10 are connections and the Bitron pins themselves.
I’ve read of instances where changing the Bitron cured the fault.
Well yes, the new Bitron comes with clean, new connecting pins.
Nothing yet about the internals failing.
The insides contain 2 CPU-like IC’s, so it won’t be worth the troubles opening up.

Kowalski · Post by **Kowalski** » 19 Feb 2006, 23:11

Mandrake wrote:
Clogzz wrote:Can't find it now, but read a story of one of the aircon bottles having a 4-wire plug, 2 thick, 2 thin.
With engine stopped, or even with the key out, shorting the 2 thick wires should turn on the compressor clutch, and shorting the 2 thin wires should start the cooling fans at low speed.
Ok, I do seem to have two thick green wires and two thin ones, although I am a bit chicken to go shorting anything out without knowing for sure what I was doing

Regards,
Simon

I can confirm the story about shorting the wires. If you're bothered about shorting stuff out and melting your wiring, short the wires using a bulb if you know what I mean.

I think you may need the engine to be running (and the air-con turned on) to get the compressor clutch to click, the same may be true of the fans.

Mandrake · Post by **Mandrake** » 20 Feb 2006, 01:26

Clogzz wrote:
Mandrake wrote:trying to work with the minimal amount of service information available
From the reading-up that I’m doing on ‘planet forum’, there is sensing for many things, including outside temperature.
Peugeot is more use with service information:

http://www.peugeotlogic.com/workshop/ws ... /ac405.htm

Thanks Clogzz,

You're a genius at digging up information like this

One question though, is this "A/C control unit" actually the same unit that people refer to as the "Bitron" in an A/C model ? It sure looks the same.

If so, how come when I unplugged this unit which I believe to be the Bitron, the air conditioning still came on and worked fine ?

(In fact I couldn't find anything that didn't work with it unplugged...

)

the small fan behind the dashboard, presumably its a big job to get access to it ?
The fan can be unclipped from the right, if I remember correctly, and dangled out.
The metal surfaces need silicone where they touch, and that’s cured my noisy fan.

Unclipped from the right of where ? You'll need to be a little bit more specific on the location than that

So could this tiny sensor circulation fan be my mystery fan noise then ? It buzzes audibly when I turn the key on even when the main blowers are turned off. (In fact my blowers wont activate when the engine isn't running anyway, which is rather annoying sitting in the car parked on a hot day

) The noise seems to come from the central vent area.

large black box with a plug with an unusual sliding lock which has a diagonal track in it...
Surprising, I have the sliding lock with diagonal track mounted on the inner wing near the battery, as if it was connecting through to the inside.

I have another black box mounted on the inner wing just in front of the battery - but it has two sockets each with 3 pins. Any idea what it could be ? I cleaned the contacts on that as well.

didn't fit it back in its proper location, I've cleaned the contacts on the socket thoroughly with LPS1
Good idea to dangle or stick it somewhere accessible.
The pins of my Bitron needed a good scrape.
A previous ordinary clean was only good for a few days.

What did you clean them with though ? I gave mine a thorough clean, but the very next day the A/C has failed to operate so I obviously havn't found the problem yet

For people that have had Bitron faults, is it usually just poor contacts that cause problems, or can the unit itself sometimes fail ?
Say that 9 cases out of 10 are connections and the Bitron pins themselves.
I’ve read of instances where changing the Bitron cured the fault.
Well yes, the new Bitron comes with clean, new connecting pins.
Nothing yet about the internals failing.
The insides contain 2 CPU-like IC’s, so it won’t be worth the troubles opening up.

Is the unit with the dry joint shown in your first link the same unit though ? If so it might be worth checking for dry joints... although it seems hermetically sealed

Regards,
Simon

Mandrake · Post by **Mandrake** » 20 Feb 2006, 01:29

Kowalski wrote:
Mandrake wrote:
Clogzz wrote:Can't find it now, but read a story of one of the aircon bottles having a 4-wire plug, 2 thick, 2 thin.
With engine stopped, or even with the key out, shorting the 2 thick wires should turn on the compressor clutch, and shorting the 2 thin wires should start the cooling fans at low speed.
Ok, I do seem to have two thick green wires and two thin ones, although I am a bit chicken to go shorting anything out without knowing for sure what I was doing

Regards,
Simon
I can confirm the story about shorting the wires. If you're bothered about shorting stuff out and melting your wiring, short the wires using a bulb if you know what I mean.

Good idea... I might give it a try with a bulb.

I think you may need the engine to be running (and the air-con turned on) to get the compressor clutch to click, the same may be true of the fans.

I'd imagine so, yes.

Regards,
Simon

Clogzz · Post by **Clogzz** » 20 Feb 2006, 13:42

Mandrake wrote:digging up information like this

Thank you.

The ‘AC control unit’ is something else than the 14-pin sealed Bitron that controls the cooling fans, and I have never come across it in my car.
The AC control unit is shown in the first link at the top right, but with only one wire going to the pressure switch.
The Bitron you have disconnected seems to be the one that controls the cooling fans, referred to as the ‘cooling fan control unit’ in the first link.
That’s the one that causes the cooling fans and STOP and temperature light to come on for no reason.
It has an input on pins 7 & 14 from the brown temperature sensor and its wiring, that also cause this fault.
That may be why removing it didn’t affect the air conditioning, but then I thought that with no cooling fans, the aircon wouldn’t work.
It cannot be opened without butchering it, but it’s not the internals that fail, only the pins that need a good scrape.
It has 14 pins tinned with solder, and I cleaned them with the rough end of a broken piece of metals hacksaw blade, then swept out the solder scraps with a paint brush, and it’s been good since.
Previous cleaning attempts with WD40 were good for only a few days.
As for what the other black box in front of the battery is, no idea, mine hasn’t got that, and may have to do with the extra frills of the VSX.

The internal temperature sensor fan is in the habit of causing a buzzing sound in the dash.
It’s held in by 2 catches, one at the left, and one at the right.
Mine came out by inserting a wide-bladed screwdriver to the right of it, between the sensor and the clock.
If there’s risk of breaking something, then removing the clock, or even the radio will improve access.
It’s energised even on the accessory position, while the cabin blower fan will only spin when the engine runs.

As for testing the compressor clutch with the engine off and the key out, it seems unlikely, though possible for the cooling fans, as they do sometimes switch on after the car is parked.
I’ll try digging up that story again, and post the finding, if found.

Clogzz · Post by **Clogzz** » 22 Feb 2006, 12:29

Found it, to cause more confusion:

http://www.frenchcarforum.co.uk/forum/v ... hp?t=13043

I can't understand how bridging pressure sensor switch contacts can engage the clutch, since the purpose of the switch is to release the clutch when sensing pressure faults.

Best of luck !

Mandrake · Post by **Mandrake** » 22 Feb 2006, 23:46

Clogzz wrote: The ‘AC control unit’ is something else than the 14-pin sealed Bitron that controls the cooling fans, and I have never come across it in my car.
The AC control unit is shown in the first link at the top right, but with only one wire going to the pressure switch.
The Bitron you have disconnected seems to be the one that controls the cooling fans, referred to as the ‘cooling fan control unit’ in the first link.
That’s the one that causes the cooling fans and STOP and temperature light to come on for no reason.
It has an input on pins 7 & 14 from the brown temperature sensor and its wiring, that also cause this fault.

Ok, I have on very rare occasions had the STOP and temperature light flicker on when the temperature is only 80 degrees, so cleaning these contacts may prevent that happening again ?

Where is the "brown" temperature sensor located ? Is that the one at the top of the radiator which has a cable running across the radiator top ?

That may be why removing it didn’t affect the air conditioning, but then I thought that with no cooling fans, the aircon wouldn’t work.

Well, when I unpluged the unit I believe to be the bitron, the cooling fans still operated with the air conditioner - at least on the normal low speed the air-con uses. Perhaps the high speed wouldn't have worked, but I couldn't easily test that.

It cannot be opened without butchering it, but it’s not the internals that fail, only the pins that need a good scrape.
It has 14 pins tinned with solder, and I cleaned them with the rough end of a broken piece of metals hacksaw blade, then swept out the solder scraps with a paint brush, and it’s been good since.
Previous cleaning attempts with WD40 were good for only a few days.
As for what the other black box in front of the battery is, no idea, mine hasn’t got that, and may have to do with the extra frills of the VSX.

I don't think its related to the suspension. There is only one control unit - the Hydractive computer which shares a box with the engine ECU, and there are a few standalone sensors, but no other control units... so I'm at a loss to know what that box does....automatic reversing mirror controller maybe ??

The internal temperature sensor fan is in the habit of causing a buzzing sound in the dash.
It’s held in by 2 catches, one at the left, and one at the right.
Mine came out by inserting a wide-bladed screwdriver to the right of it, between the sensor and the clock.
If there’s risk of breaking something, then removing the clock, or even the radio will improve access.

Ok thanks. I have the radio out at the moment anyway, so that will probably help. As long as I can get to it I'm sure I can fix it. Ah..... so its behind that little gril that sometimes has an alarm LED in the middle of it ?

Regards,
Simon

Clogzz · Post by **Clogzz** » 23 Feb 2006, 14:14

Hello Simon,

Mandrake wrote:STOP and temperature light flicker on, cleaning these contacts may prevent that happening again ?

Yes, that’s what’s cured it for good on mine.
Contrary to what I wrote above, the cooling fan Bitron has 15 pins instead of 14.
It has one row of 8 pins, and a second, offset row of 7 pins.
Not all pins are used, there are, I think, 2 empty terminals in the loom socket.

the brown temperature sensor located ?

That’s very different to mine, which hasn’t got any sensor or wire at the top of the radiator.
Annoying to find that there are that many differences between versions of the same car.
Probably that the designers had bottles of plonk under their desks.

The brown sensor is normally screwed into the back of the thermostat housing, along with 2 other temperature sensors, and it’s impossible to see, or even to reach them, at least through the top.
Maybe that you can see and reach them from underneath, but I’ve never been there, as I’m not equipped to safely hold up the car.

unplugged the bitron, the cooling fans still operated with the air conditioner

Well, that would indicate that this Bitron is something else, that mine doesn’t have.
That may be the one that has to do with what I called the ‘extra frills’ of the VSX.
By 'frills' I meant equipment like motorised and automatic reversing mirrors and motorised seats, and wasn’t thinking of the suspension.

behind that little grill that sometimes has an alarm LED in the middle of it ?

Yes, it’s in there, a 2-pin temperature sensor, and the buzzing fan motor.

__________________________________________________________

Quick fiddle with the air conditioning pressure sensor plug today.
With engine running, and aircon switched on, pulled the plug out, and the aircon clutch released silently, but the fans kept spinning at the low speed.
Put it back in, and the clutch engaged again.
Tried several times, always the same.
This confirms that the sensor has ‘normal pressure’ sensing, besides high and low pressure sensing.
More experiments to come, will post.

Regards,
Terry.

alan s · Post by **alan s** » 24 Feb 2006, 07:12

Some of those pressure switches on top of the receiver are HP/LP controls.
If the pressure gets too high, one set of contacts open circuit. If you dump the gas and the compressor begins to go into vacuum, another set opens.
Either one will break the circuit to the copressor clutch.
Unfortunately, Governments being Governments and publiuc servants being cantankerous by nature, it seems no two countries carried the same regulations when we switched from R12 to 134a and various other carcinogens they use for refrigerants, so as a result, what may be the norm in Australia may be different in NZ and different again in the UK. By the same token, they also could be the same, so it's not easy at times diagnosing in other countries.

Alan S