Intermitant Xantia Air-Con ?

Mandrake · Post by **Mandrake** » 04 Sep 2005, 07:06

Hi All,
Finally we're heading into Summer down here [:D] and I've started to try and use the Aircon in my Xantia and discovered it seems to have a mind of its own.
Sometimes it will work really well, when it is working it only takes about 10 seconds for the air temperature coming in the vents to drop to a nice chilly temperature with an outside temperature of 25+, but other times it will simply not work at all.
When it doesn't work, the light comes on with the switch, but there is no change in air temperature at all. It's quite hard to tell from inside the car whether the compressor and fans are coming on or not, as even when they do work you can't really notice anything except a brief drop in engine revs if idling.
A few questions:
Are there any other factors other than the signal from the gas pressure safety cut-out switch and the aircon on/off dashboard switch that might not allow the aircon to come on ? For example will it refuse to activate if the outside ambient temperature is below 20 degrees or so ?
Since I bought the car a couple of months ago its only in the last 2-3 weeks that we've had sunny days 22 degrees or more that I've started to try and use the aircon. At first I assumed it wouldn't activate when the outside ambient temperature was only 16-18 degrees (making it impossible to test at the time I bought it) but now I'm not so sure...
Are there any deliberate time delays in the system under certain circumstances ? EG am I being impatient if I press the switch and don't get cold air in 10 seconds ?
Does the thermostat control have any say in whether the aircon is cycled on or off or does it just blend in hot air with the cooled air to reach the desired temperature ? (Thats the impression the owners manual gives)
Could a blocked pollen filter stop the aircon from activating in any way ? (EG does it measure airflow ?)
I've noticed that sometimes if the aircon is turned on I seem to get cold air almost regardless of the temperature setting or ambient temperatures - its not until I turn it up to nearly 26 that the air blending system brings in some warm air, even though the ambient temperature is (say) 22 degrees.
Is it possible the gas pressure in the system is marginal and only activating the pressure cutout switch intermitantly ? I wouldn't have thought the pressure was low, as when it does activate it seems to be very efficient, unlike a system that has low gas and struggles to cool the temperature.
I don't have much experience with car air conditioning systems, so where should I start looking ?
Regards,
Simon

Clogzz · Post by **Clogzz** » 04 Sep 2005, 18:09

The air conditioning must turn on irrespective of the outside temperature.
In cold, rainy weather, the aircon is used to demist the windows.
This sounds like an intermittent switching fault.
To check on the operation, lift bonnet, stand at driver's door, switch on the aircon, and check that the fans come on at low speed, and that the compressor clutch clicks in.
The interior fan must also be set to either 'auto' or one of the fixed speeds.
If it's set to 'off', the aircon won't work either.

pete_wood_uk · Post by **pete_wood_uk** » 06 Sep 2005, 17:50

Simon, I posted a question about quite similar behaviour in my 97 TD a while ago. Didn't get any answers, unfortunately. I find that mine will come on reliably when the engine is warm (which may be related to engine temperature, or to the fact that the engine has recently run). Won't come on with a cold engine - light comes on on dashboard, but no compressor clutch. Wait til engine warms up, then reset the system - ignition off, then on again, and the compressor clutches in and runs reliably. No idea, and can't be bothered to spend a weekend looking for it...
Cheers
Pete

Mandrake · Post by **Mandrake** » 06 Sep 2005, 18:09

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by pete_wood_uk

Simon, I posted a question about quite similar behaviour in my 97 TD a while ago. Didn't get any answers, unfortunately. I find that mine will come on reliably when the engine is warm (which may be related to engine temperature, or to the fact that the engine has recently run). Won't come on with a cold engine - light comes on on dashboard, but no compressor clutch. Wait til engine warms up, then reset the system - ignition off, then on again, and the compressor clutches in and runs reliably. No idea, and can't be bothered to spend a weekend looking for it...
Cheers
Pete
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Hi Pete,
Since the pulley on the compressor turns all the time, how are you determining when the clutch activates ? Also when it wasn't working for you, was turning the air conditioning switch on turning on the radiator fans ?
So far every time I've checked, the switch does activate the radiator fans, even when I don't seem to be getting any cooling...
Hopefully the weather gods will give me some more hot days to test it on, it's been a bit cold again this week... [:D]
Regards,
Simon

Post by **RichardW** » 06 Sep 2005, 18:16

I think there is a min air temp for the A/C to work - it's about 4°C which stops the evaporator icing up. I think the A/C cycles the compressor based on the temperature of the evaporator, if you want it hotter, then you blend in some hot air as you suggest. My TD takes quite a few seconds before the clutch engages after the swtich is pressed, and I'm a bit low on gas, so it doesn't got instantly cold. If it's a definitely a full go / no go situation, then it's probably a switch somewhere not making (like the pressure switch), or bad earth on the compressor clutch. It may also give trouble if the cooling fans don't start though. With the A/C swtiched on, both cooling fans should run on low speed all the time - regardless of whether the compressor is running or not.

oscarloco · Post by **oscarloco** » 06 Sep 2005, 23:23

Had a very similar problem with my aircon but since the wheater in my counrty is normally warm - hot (20 - 28 Celsius), I was sweating a lot because it worked fine and then, it would stop working, altough I could hear the fans coming in but there was no compressor enganing.
Turned out to be the cables that go into the aircon compressor, I disconnected and connected them a couple of times and Voila, cold air all day!

Mandrake · Post by **Mandrake** » 07 Sep 2005, 03:31

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by oscarloco

Had a very similar problem with my aircon but since the wheater in my counrty is normally warm - hot (20 - 28 Celsius), I was sweating a lot because it worked fine and then, it would stop working, altough I could hear the fans coming in but there was no compressor enganing.
Turned out to be the cables that go into the aircon compressor, I disconnected and connected them a couple of times and Voila, cold air all day!
<hr height="1" noshade id="quote"></blockquote id="quote">
Great idea! I'll check the cables to the compressor carefully and spray the plug contacts with some LPS.
Summer here is much the same range - about 22 to 28 typically, and yes, I was sweating with all the windows open last summer in my previous car which didn't have working air conditioning, hence the desire to get it working properly now that I have aircon [:D]
Regards,
Simon

wotsupnow · Post by **wotsupnow** » 07 Sep 2005, 16:15

My Xantia is similar, at tickover fans spin but compressor clutch doesn't engage, above 1500rpm the clutch then kicks in so I suspect a bad connection/low voltage somewhere. NB I found the fuse for the aircon in the car had 12v either side but where it appears at the relays there was only about 9v and adding the slightest of loads dropped it to zero so must be a corroded connection along the way but couldn't see where the cables route. I stuck a diode from the live feed to this point ( tucked ends of diode in relay sockets before plugging in relays ) and fans have worked fine. I found the bitron unti behind the n/s front hlamp and that is nice and clean but I would like to know where the wiring runs from that fuse.........
Pete

Mandrake · Post by **Mandrake** » 07 Sep 2005, 17:39

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by wotsupnow

My Xantia is similar, at tickover fans spin but compressor clutch doesn't engage, above 1500rpm the clutch then kicks in so I suspect a bad connection/low voltage somewhere.
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I had a quick look today and just with the car idling tried turning on the air conditioning - sure enough the fans came on after about a 4 second delay, but there was no dip in engine revs and no cool air, thus the compressor most likely not engaging.
After unplugging the cable to the compressor and reconnecting it, the next time I tried it the compressor did seem to activate (just noticable drop in engine revs) and the air did seem slightly cooler.
Not conclusive yet as the ambient temperature was only 17 degrees at the time of the test, so even when it's running the extra coolness is not obvious like it is on a 25 degree day [:D]
So it looks like the (lack of) operation of the compressor clutch is indeed the problem, although the exact cause is yet to be proven. I'll give the plug a good spray with contact cleaner and see how it goes.
<blockquote id="quote">quote:<hr height="1" noshade id="quote">
NB I found the fuse for the aircon in the car had 12v either side but where it appears at the relays there was only about 9v and adding the slightest of loads dropped it to zero so must be a corroded connection along the way but couldn't see where the cables route.
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Where are the relays that you're refering to ? Are they near the fuse box somewhere ? Or are you measuring the voltage at the plug going to the compressor right close to the compressor ?
<blockquote id="quote">quote:<hr height="1" noshade id="quote">
I stuck a diode from the live feed to this point ( tucked ends of diode in relay sockets before plugging in relays ) and fans have worked fine.
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I'm not sure that I understand what you've tried to do here - what you say doesn't really make sense ? Is this the feed to the compressor clutch, or the feed to the fans ? Are you saying your fans WERENT working before ? In any case it doesn't sound like a good idea, especially without seeing a circuit diagram of it..
Regards,
Simon

ghostrider · Post by **ghostrider** » 08 Sep 2005, 03:20

Timboskinimbo had similar probs and was taking it to a main stealer to put on their diagnostic computer to identify the problem but I've not heard what the result was.
I have similar problems and so far I've spent a small fortune and been unable to get it to work reliably, AlanS is the man for this problem, but bearing in mind the A/C is controlled by 1. the Bitron 2. The A/C ecu 3. The engine management ECU, if it is not a simple electrical fault, a lack of gas or moisture in the system needing a new drier bottle I suspect the chances of getting it to work are relatively slim. Why they have to make it so complex is completely beyond me, after all as someone pointed out to me it's only a bl***y fridge when all is said and done.
As to whether the compressor clutch is engaged or not if you look down from above at the compressor pulley you will see some bolt heads sticking out from the outside edge of it, when the clutch is engaged you wont be able to see them as they are rotating with the pulley.
As a matter of interest try holding the microswitch on top of the injection pump in the closed position whilst you open the throttle ( I used a tie wrap) and see if it runs then, it fixed mine for a while but now it is intermittent again.
Check those cooling fans are genuinely running at half speed, again one of mine had worn brushes so only ran intermittently ( mostly when I was looking at it !!) Thanks for that one Alan. Replaced fan motor, no different, but did the arcing that must have occured as the brushes didn't make contact properly damage any of those ECUs? Who knows, but temporarily I've given up
Pete
________
NEW MEXICO DISPENSARY

rossnunn · Post by **rossnunn** » 08 Sep 2005, 03:44

I'm asuming yours doesn't have climate control? just plain air con??

Mandrake · Post by **Mandrake** » 08 Sep 2005, 04:12

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by rossnunn

I'm asuming yours doesn't have climate control? just plain air con??
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Who of the many people in this thread with the same problems are you asking ? [:D]
If you're asking me, then you'll have to tell me first what the difference between air conditioning and climate control is so I can tell you what mine has....[;)]
Regards,
Simon

Mandrake · Post by **Mandrake** » 08 Sep 2005, 04:19

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by ghostrider
As to whether the compressor clutch is engaged or not if you look down from above at the compressor pulley you will see some bolt heads sticking out from the outside edge of it, when the clutch is engaged you wont be able to see them as they are rotating with the pulley.
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Ok thanks, I'll have a look with a torch on the weekend to try and establish whether it is engaging reliably or not.
<blockquote id="quote">quote:<hr height="1" noshade id="quote">
As a matter of interest try holding the microswitch on top of the injection pump in the closed position whilst you open the throttle ( I used a tie wrap) and see if it runs then, it fixed mine for a while but now it is intermittent again.
<hr height="1" noshade id="quote"></blockquote id="quote">
Injection pump ? Are you refering to the injection pump for the engine ? If so I would point out my car is the 8 valve 2 litre petrol, and not a diesel, so I don't know if that has any bearing on it..
<blockquote id="quote">quote:<hr height="1" noshade id="quote">
Check those cooling fans are genuinely running at half speed, again one of mine had worn brushes so only ran intermittently ( mostly when I was looking at it !!)
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Yes, I've confirmed that both fans are running at half speed on at least one occasion when the aircon didn't seem to be working, so that is definately pointing towards activation of the compressor clutch. As far as I know the fans are operating fine.
Regards,
Simon

Mandrake · Post by **Mandrake** » 08 Sep 2005, 06:32

I think I may have cracked it here [:D]
Nice hot 27 degree day today, so I grabbed my can of LPS 1, unplugged the plug in the compressor cable near the bottom of the radiator, gave it a good squirt on the contacts, plugged it back together and apart a few times to clean the contacts, and did the same on the connector to the pressure switch on the top of the drier (?) bottle as well for good measure.
Started up the engine, and with a cold and idling engine pressed the A/C switch, and presto, very cold air within 10 seconds. [:D][:D]
I notice that it's behaviour has changed compared to before - previously when it did seem to be working there would be a brief and very small drop in engine revs when the compressor tried to start, and then it would rise again.
Now, there is a quite considerable (100rpm) drop in engine revs that stays that way the entire time the A/C is on, and there is a very audible "CLICK" at the same time that can even be heard from inside the car with the doors closed, that I never heard before.
I switched it off and on at least 5 times to confirm it really was working, each time I turned it on I got the 100rpm drop in idle speed, a loud click, and cold air within 10 seconds or so.
Assuming it keeps working over the next few days I think it might be fixed [:D]
My theory is that there was a high resistance connection on the feed to the compressor clutch which would have caused a voltage drop under the load of the compressor clutch solenoid, so that the clutch would have sometimes not engaged at all, and other times only engaged partially.
In the partial engagement state it may have been turning the compressor, but only slowly due to the clutch slipping a bit - thus not much change in engine revs, and less than 100% effective cooling.
The "CLICK" will be a good sign of the clutch snapping into action solidly, which it wouldn't have been doing before.
I'll post an update in a week or so to let you all know if its still working...
Thanks for all the suggestions and information...
Regards,
Simon
PS I gave the same LPS treatment to the plug going to the Hydractive 2 control block solenoid as well - as it is the same type of connector and it may partly explain some of the intermitant harsh ride problems I've been trying to chase down...

PeterMann · Post by **PeterMann** » 08 Sep 2005, 15:51

I had similar symptoms with my Xantia aircon. Fixed by replacing pressure switch on filter/condenser. Probably just needed clean and oil of connectors of pressure switch. So, now I have a spare connector switch.