Xantia air con question

[Jaf]

Hi guys. My air con takes 5 mins to get to 20, an hour to get down to 14, then another half hour and it's down to 8. This is with outside temps of 35 or so. It was regassed a month ago, the chap said it had lost half its gas in 2 years so not too bad. He thought there could be a problem with a switch. Though not an expert he's the best of 4 places I've tried, including Citroen.

Any ideas please?

Thanks.

[GiveMeABreak]

Well for that temperature, I wouldn't say that is too far off. They always recommend in very hot temperatures where the car has been standing, to drive with all the windows down for a while to evacuate most of the heat - that's half the battle. You could then keep the air recycling on for a while to help the system cool the interior before switching back to fresh air.

Assuming you don't have a gas leak in one of the pipes or the condenser, have you had the system cleaned out - some garages evacuate all the oil and refrigerant from the circuit clean it and then refill - as opposed to a simple recharge of the gas. For an 18 year old car - has it been cleaned out ever?

Remember that when the gas gets low, the compressor has to work twice as hard to maintain cooling.

[Jaf]

Thanks Marc. My hunch is that the regas didn't go well. I really should have turned around straight away and complained as I think it worked better before! Last summer the temp got down to 8 within about 10 mins, this is measuring the air coming out of the vent.

The car has only ever had simple vacuum and regas, a second hand compressor 4 years ago with some dye beforehand to find the leak. I've had the car 9 years, 100,000kms. I would gladly pay to get it fixed (normally do my own spannering) but it's proving impossible to find a decent garage!

I wonder if there are any electronics involved? I know there's a cut off for low/ high pressure. Is the temp set electronically?

[waynedance]

Mine was working intermittently recently and it turned out to be the evaporator temp sensor in the heater box.

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[Jaf]

Thanks waynedance. Did you fix it yourself?

Went to the garage again. No loss of gas, compressor runs when switched on, fans run. So....could the compressor be struggling, or the evaporator temp sensor, or LP/ HP switch, can the fan belt run the compressor in the wrong direction (grasping at straws! Changed belts in Jan). Would the dryer filter affect it?

I understand that the mark 2 xantia should switch the air con on when the cabin vents are switched to demist. This has never happened, even when the air was working well.

I shall hunt out the wiring diagrams and send my dad hunting with his meter.

[xantia_v6]

I understand that the mark 2 xantia should switch the air con on when the cabin vents are switched to demist. This has never happened, even when the air was working well.

While that is generally true, I am not sure that 1998 cars had that feature, so don't go to too much trouble looking for it.

Have you measured the temperature of the air leaving the vents?

[waynedance]

I did end up fixing the car myself after being pointed in the right direction from a diagnostic machine. There was a fault code in there for the evap temp sensor faulty reading.

Good luck fixing.

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[Jaf]

Ooh interesting. I thought that since the car is mostly mechanical it would not have any fault codes. I shall book her into Citroen. Wonder if I should buy a Lexia.

You're right about the demist, I'm not going to worry about it!

[xantia_v6]

I would recommend getting a Lexia, unless you are thinking of giving up ownership of all PSA cars in the near future...

[waynedance]

Any decent diagnostic machine should do it, one I used was not a Lexia but did have that to hand if needed.

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[c.morewood]

Sorry to disappoint Fred, but I'm pretty sure that the Lexia won't read the aircon on a Xantia, especially one as old as'98. It doesn't read my '99 & '00 Xantia aircon.

[xantia_v6]

It depends on the Lexia clone. A genuine Lexia can read the AC ECU (I have seen it), but some clones (including mine) can't.

[Harlequin]

whilst not a xantia - my 1998 synergie , switches the aircon on when demist is presssed

[Mandrake]

A proper Lexia will read the climate control ECU of a 1998 Xantia. I was able to read my 1998 S2 V6 climate ECU and there is a lot of information available including:

All temperature sensors - this includes the one on the evaporator which might be faulty as well as the upper and lower vent sensors and ambient sensors. (I think there are 4 air temp sensors in total)

It will also read the position of the slide controls on the dashboard and state of the aircon switch.

You can also manually engage the compressor and adjust the hot/cold mixer flap under Lexia control.

With all this information it's quite easy to diagnose whether there is a problem or not by watching the temperature readings of the various sensors.

One thing that springs to mind is icing of the evaporator if its fins are full of dust. This will cause it to get too cold and this will be measured by the evaporator temperature sensor which will cause the ECU to disengage the compressor to prevent freezing of the evaporator. On a Xantia this cutout occurs at around 2-4 degrees as measured at the evaporator.

Or another thing that may happen is the evaporator sensor is faulty which causes the compressor to keep running until the evaporator fins ice up - this then blocks the air flow and kills the effectiveness of the system. Only after it has been turned off for a while can the ice melt and the airflow resume.

I would put it on a Lexia and monitor the readings whilst in use - that should give a good idea where the problem is.

With the other work that has already been done my guess would be evaporator icing.

PS I presume the pollen filter has been replaced and there is plenty of airflow through the vents ? If the airflow is restricted it will also cause the evaporator to get too cold and the ECU to keep cycling the compressor off to avoid freezing the evaporator.

[Jaf]

Very interesting Simon, thanks.

Went to Citroen, asked to book it in to put it on the Lexia, fella said basically go away it's a fault with the compressor. Without moving an inch from under the car he was working on. Ffs. Need to learn some Spanish swear words!

Went to another fella with a Lexia, had a row about it having an air con ecu. Put it on the Lexia but he had the newer software so it wouldn't get into it. Aargh. He tried other code readers but they didn't work. He said change the dryer as electrics would just turn the compressor on/ off. Ffs.

Will see tomorrow if Juan in the other village has an old lexia. Otherwise I will try again at Citroen. Would really like the fault codes at least, if I could get into the controls it would be so telling.

Who wants a holiday to lovely Spain!!!

I am reading up about the heater controls now. On the way home fiddling around with the temp controls, the air was cooler with the slider set at 22 than blue. It was 24 outside, with the slider on blue the air was 18, with the slider on 22 it was 14. (On 24 it was 24, on hot it was over 70) Very odd. Will see if it happens again tomorrow.

Watching the compressor clutch for 20mins at tick over it stays engaged. Pollen filter is new.