No power to the compressor!

davetherave · Unread post by **davetherave** » 21 Jun 2009, 09:32

You could be right, but the aircon did work for about 2-3 weeks, i will be asking them at kwick fit to test for any leaks, but surely i would have noticed a leak that big!

Thanks for taking the time to think about it! I really hope i dont have to go leak hunting, i wouldnt even no where to start

I shall report back hopefully witht eh results of the pressure test!

davetherave · Unread post by **davetherave** » 21 Jun 2009, 12:33

Ok i got them to test the system, and if removed very little refridgerant, and absolutly no compressor oil!

So between us we think that as the compressor also seems a bit oily, it has leaked out through the compressor, as the system did not detect any leaks when it pressurised it

So it is all drained now, and hopefully 2moro i will remove the compressor and replace the drier!
If that doesnt work then i dont know what will!

Clogzz · Unread post by **Clogzz** » 22 Jun 2009, 05:39

Colin, you're rapidly turning into our aircon specialist

litigation ... plagiarism

You're welcome, Colin !

My home computer is deranged, and it's good to see all that going by itself.

Unread post by **admiral51** » 22 Jun 2009, 20:34

You're welcome, Colin !

Thanks Clogzz will tell the solicitor hes no longer on a retainer

Unread post by **Dommo** » 28 May 2010, 15:16

admiral51 wrote: Hi dave
That is setting alarm bells ringing

Dont take this as gospel but this is how i understand the system to work
1.Everything is controlled by the information sent/recieved by the Bitron sensor
2.The A/C needs the following things to be inplace before it will start
3.The A/C button must be switched to the on position
4.The interior fan must be switched on/auto
4a.Caviat on MK2 cars if the interior slider is set to demist screen then the A/C will switch on
5.Both fans must run at slow speed.Bitron sensor cannot tell if fans are actually running it only knows if power has been succesfully applied to them
6.Power is then sent to HP/LP switch
7.If HP if detected then both fans are set to full speed and A/C disabled until HP is no longer present
8.LP in system will prevent compressor from engaging

If as you say both fans go high speed when you engage the A/C then i would point the blame at the switch as this is saying the system is under HP even though it hasnt started.
Try starting the A/C with the pressure switch plug disconnected and see what happens to the fans.The compressor shouldnt kick in as the Bitron is not recieving any information from the HP/LP switch so cant commit to doing anything other than starting the fans at slow speed something it should do before it sends power to the HP/LP switch.

You should (hopefully ) find that the fans spin at slow speed and you will then be able to bridge the 2 thick wires in the plug to engage the compressor clutch.
If the fans spins at full speed with the plug pulled then i would suspect a wiring fault/short to ground in the thin wires leading to plug

Hope this sort of helps

Colin

PS If it is the switch i think i have a good spare i can pop in the post to you FOC

Sorry I know this is a topic from a long while ago, but if these criteria are correct, what do we think is the issue with my 306?

Basically, in accessories mode, AC button illuminated, the AC compressor will engage, as it should. Turn the key to the 'run' position, and the compressor disengages, turn the engine on, so the key is now in the 'run' position, but the engine is running, the compressor is still disengaged with the fans running on low speed. Now, if I rev the engine over about 1250 RPM, the AC compressor engages, until the revs drop below 1250 or so RPM. When the compressor is engaged, the AC works really well, the air coming out of the vents is much colder than the outside ambient temperature, 'ice cold' as people say... Until the revs drop to idle.. Argh!

Any thoughts would be much appreciated

Dom.

Unread post by **admiral51** » 28 May 2010, 21:38

Hi Dom
First off im a not an A/C expert all knowledge has been gained from this forum and practical repairs on a Xantia

A little unsure how you can be sure the compressor is engaged without the engine running with the key in the accessories position unless ive misread your post.

For my sins i am trying to collate as much info on the Xantia (sorry thats all i know about) A/C system that has been posted on the forum but have a look at This

I cant find the link at the moment but there is a purple/violet relay in the fusebox by the abs ECU that controls the cut in/out of the A/C.It has been known to develop a fault .
It could be that your system is borderline on gas and with the revs higher than 1200 the sensor is assuming you are travelling and can cope with the increase of heat in the system.As soon as you drop to idle the heat within the system will increase and its safety feature will be to disengage the A/C .
Like i say im no expert,just trying to remember what ive gleaned from the forum

Colin

Clogzz · Unread post by **Clogzz** » 29 May 2010, 12:34

If the air is ice cold above 1250 rpm, there’s plenty to compress, and a good load on the accessory belt.
If the belt is slightly loose, the heaviest driven accessory will slip first.
The belt on SWMBO’s Nissan Pulsar was slightly loose, and we only found out because there was a slight whine above 50 mph.

Unread post by **Dommo** » 29 May 2010, 13:08

Hi Colin, thanks for the input

admiral51 wrote:Hi Dom
First off im a not an A/C expert all knowledge has been gained from this forum and practical repairs on a Xantia

A little unsure how you can be sure the compressor is engaged without the engine running with the key in the accessories position unless ive misread your post. You can hear the compressor click, it's very loud! Probably easier to hear in a 306 than a Xantia, they didn't do a particularly good job of sound proofing the 1.9TD 306 engine bay. But yeah, you can hear it click in, and hear it click off with the engine off (the sound of it clicking on is louder than it clicking off)

For my sins i am trying to collate as much info on the Xantia (sorry thats all i know about) A/C system that has been posted on the forum but have a look at This

I cant find the link at the moment but there is a purple/violet relay in the fusebox by the abs ECU that controls the cut in/out of the A/C.It has been known to develop a fault . As it happens, I know the relay you're talking about, and I can feel that click on/off when the compressor engages, so something is telling that relay to turn off
It could be that your system is borderline on gas and with the revs higher than 1200 the sensor is assuming you are travelling and can cope with the increase of heat in the system.As soon as you drop to idle the heat within the system will increase and its safety feature will be to disengage the A/C . I wondered about this, but I don't know how the AC system knows the engine speed, there's nothing to my knowledge that could tell the AC system what the engine speed is, there's no wires coming from the fuel pump or anything, so unless it uses the same sender as the clocks I don't think it knows engine speed?
Like i say im no expert,just trying to remember what ive gleaned from the forum

Colin

Sorry for the questions, it's just confusing me! Stupid car

Thanks again Colin.[/b]

Unread post by **Dommo** » 29 May 2010, 13:11

Clogzz wrote:If the air is ice cold above 1250 rpm, there’s plenty to compress, and a good load on the accessory belt.
If the belt is slightly loose, the heaviest driven accessory will slip first.
The belt on SWMBO’s Nissan Pulsar was slightly loose, and we only found out because there was a slight whine above 50 mph.

Yeah, I thought that. And I don't think it's pressure related as I bypassed the pressostat thing (for testing purposes) a good few months ago and from what I remember, it still had the same issue. But I ought to do this test again to check as I can't remember if it did fix the problem or not

aneesh84 · Unread post by **aneesh84** » 09 Aug 2011, 18:01

CitroJim wrote:Hi Dave,

This is the circuit of the MK2 aircon system and the compressor clutch is item 8020.

It should help track it down. If you need the harness diagram, let me know...

Hi Jim, could help me find the relay 8015 in your diagram (compressor cut off relay (controlled by coolant temperature control unit) ). Is it behind the fuse box?