Aircon Won't Engage

[alexjfisher]

Hi

 

I'm having problems with my C5's (58 plate 2.0 HDI tourer) aircon.  I took it to be serviced a couple of weeks ago, and the garage was unable to get it going.  It's got a full charge of coolant, but the compressor clutch refuses to engage.

 

I spent about an hour with my mechanic trying to find the fault, but we didn't get very far.  He suggested I might do some research online, so here I am! :)

 

We hooked it up to his 'snap-on' diagnostics machine and were able to actuate the compressor clutch manually (but only when the engine wasn't running).  There was one sensor value that looked way off and could be to blame.  IIRC it was the 'exterior air temperature' value that was reading 158 degrees Fahrenheit.

Does the car have a second external air temperature sensor just for the aircon? (because the outside temperature as displayed on the satnav is fine).

 

I bought a citroen service manual off ebay and have been trying to study the exploded diagrams, but it's not at all obvious.

 

Many thanks for your help,

Alex

 

 

[paul.h]

Welcome to the forum.

 

The air con will not run if the outside temperature is measured as below 6°C. So if the car thinks it is below this or maybe outside an expected value due to a fault, then probably it will not run. 158°F = 70°C so this would appear to be at fault.

 

Other possibilities include high or low refrigerant pressure, low temperature at the evaporator matrix, cabin fan not running, high engine coolant temperature, radiator fan not running. If your garage is not a Citroen dealer or specialist with the Citroen Lexia diagnostic equipment it may be worthwhile trying one.

[alexjfisher]

Thanks Paul.

 

I agree, if the car really thought the outside air temperature was 70°C that'd be a pretty good reason to not engage the aircon (I doubt the condenser would actual condense anything at that temperature!)

But, most of my research so far suggests the car should be using the standard wing mirror sensor (that feeds the satnav display and is reading correctly) to determine the outside temperature.

 

If there is a separate sensor, does anybody know where it might be?

 

With regards to Lexias, are they worth the £100 they seem to be going for on ebay?

Thanks again,

Alex

[PICASSOCONVERT]

Alex

 

Welcome to the forum. I bought Lexia from eBay recently and it helped me to sort out the problems with my C5 (2003, so older than yours). I have no training as a mechanic of any sort but I managed to work my way through the menus without difficulty and solved a couple of issues comparatively easily.

 

David

[paul.h]

Maybe the 158°F was not the outside temperature but from one of the other sensors - maybe inlet air temp to the engine or coolant temp., both of which will be shown by a low cost code reader with live data (but not the outside air temp from the mirror sensor)

[coastline taxis]

Hi just a couple of thing.

Assuming you have checked all fuses and wiring and checked the power going into the aircon pump itself with a power probe/tester

Plug the snap on back in and go to acuator tests or special function and test the low speed cooling fan (on the radiator) as this will stop the aircon.

Has your model got the dual climate control

[paul.h]

If you have measured the refrigerant high and low pressures, there is some info in this post that may be of use http://www.citroen-owners-club.co.uk/citroen/topic/20433-manual-aircon/

[alexjfisher]

Alex

 

Welcome to the forum. I bought Lexia from eBay recently and it helped me to sort out the problems with my C5 (2003, so older than yours). I have no training as a mechanic of any sort but I managed to work my way through the menus without difficulty and solved a couple of issues comparatively easily.

 

David

 

Thanks David

Do you know how much space it takes to install the software.  Last week I installed some service documentation on an old laptop and it's left me with only around 1GB of space left (the service manuals took up over 25GB!)

[alexjfisher]

Maybe the 158°F was not the outside temperature but from one of the other sensors - maybe inlet air temp to the engine or coolant temp., both of which will be shown by a low cost code reader with live data (but not the outside air temp from the mirror sensor)

It was an almost constant 158 degree reading (flipped between 158 and 157.5 IIRC) and was the same whether the engine was running or not.  But, since it wasn't a citroen tool being used, perhaps it is just a red herring.  I might buy a Lexia and see if it shows the same value.

[alexjfisher]

Hi just a couple of thing.

Assuming you have checked all fuses and wiring and checked the power going into the aircon pump itself with a power probe/tester

Plug the snap on back in and go to acuator tests or special function and test the low speed cooling fan (on the radiator) as this will stop the aircon.

Has your model got the dual climate control

 

We checked all the fuses, and we can hear the compressor clutch activating when manually commanded from the snap on.  Testing the cooling fan is a good idea.  Thanks.  The only problem being I don't own the snap on and I think my mechanic is fed up of seeing me! (my C5 spent a combined total of two months in the garage at the start of the year after an injector failed...).

I think I'll invest in the Lexia.  If I don't get much use out of it, I'll probably be able to sell it on.

[alexjfisher]

 

Hi just a couple of thing.

Assuming you have checked all fuses and wiring and checked the power going into the aircon pump itself with a power probe/tester

Plug the snap on back in and go to acuator tests or special function and test the low speed cooling fan (on the radiator) as this will stop the aircon.

Has your model got the dual climate control

 

We checked all the fuses, and we can hear the compressor clutch activating when manually commanded from the snap on.  Testing the cooling fan is a good idea.  Thanks.  The only problem being I don't own the snap on and I think my mechanic is fed up of seeing me! (my C5 spent a combined total of two months in the garage at the start of the year after an injector failed...).

I think I'll invest in the Lexia.  If I don't get much use out of it, I'll probably be able to sell it on.

 

Forgot to say, yes, mine does have the dual climate control system fitted.  Thanks again for your help.

[paul.h]

One thing to consider, if the fix involves anything that needs the refrigerant to be removed such as a compressor or pressure switch fault, then it will need to be done by a garage with the equipment to remove and refill the gas. If so and you use a Citroen dealer they would diagnose the fault as part of the work and and it would save the cost of buying a Lexia (unless you want one anyway) or paying somebody for a diagnostic check.

[alexjfisher]

 

Hi just a couple of thing.

Assuming you have checked all fuses and wiring and checked the power going into the aircon pump itself with a power probe/tester

Plug the snap on back in and go to acuator tests or special function and test the low speed cooling fan (on the radiator) as this will stop the aircon.

Has your model got the dual climate control

 

We checked all the fuses, and we can hear the compressor clutch activating when manually commanded from the snap on.  Testing the cooling fan is a good idea.  Thanks.  The only problem being I don't own the snap on and I think my mechanic is fed up of seeing me! (my C5 spent a combined total of two months in the garage at the start of the year after an injector failed...).

I think I'll invest in the Lexia.  If I don't get much use out of it, I'll probably be able to sell it on.

 

 

Testing the cooling fan was certainly a good idea!  Forget low speed cooling fan.  High speed doesn't work either!  I bought the Lexia and the fault code, IIRC, is 'fan high speed control'.

As well as the fault code, I went for a blast around the bypass and then parked up with the engine running.  The fan never came on.

 

So, it could be the fan itself (expensive?), or the fan relay (cheap?).  Any thoughts on how best to diagnose?  All I've figured out so far, is the maxi fuse hasn't blown (took a while to find though!), and the fan hasn't seized (it spins nice and freely).

 

Thanks,

Alex

[coastline taxis]

You really need the diagnostic tool to solve it .  but anyway there was a problem with the relays on the cooling fan corroding there next to the radiator on the suport panel under a black cover. Disconect the fan and take a live to it and see if it spins other thing to check is the engine temperature gauge although the command for aircon should overide this. What area are you in as there are members on here that will help free

[paul.h]

When I have checked our C3 the fan would start with the engine temp at 96°C and stop when dropped back to 94°C, did you check with the Lexia what the temp got to ?

 

Also, there may be some more fuses you could check - at the side of the battery may be a red fusebox BFDB which according to the French RTA manual for the C5 has special bolted fuses in and the middle one F3, 60 amp is for 'groupe motoventilateur 2' - so you need to have  a look at this as well as the maxi fuse MF1 50 amp listed as 'groupe motoventilateur' on the bsm/PSF1 engine fusebox. It also has the engine fuse box fuse F21 has something to do with it.

[alexjfisher]

I got up to 108°C as read from the Lexia (I'm guessing that this isn't above boiling point as it's pressurised) and also did the high speed fan actuator test.  Right now, I'm less concerned about the aircon and more about having no cooling (although I'm hoping fixing the cooling fan will also get the air con working again).  I've got a 500 mile round trip planned for next weekend...

 

 

Also, there may be some more fuses you could check - at the side of the battery may be a red fusebox BFDB which according to the French RTA manual for the C5 has special bolted fuses in and the middle one F3, 60 amp is for 'groupe motoventilateur 2' - so you need to have  a look at this as well as the maxi fuse MF1 50 amp listed as 'groupe motoventilateur' on the bsm/PSF1 engine fusebox. It also has the engine fuse box fuse F21 has something to do with it.

Another hidden fuse box!  Thanks, I'll have a look for that.

 

 

 but anyway there was a problem with the relays on the cooling fan corroding there next to the radiator on the suport panel under a black cover. Disconect the fan and take a live to it and see if it spins other thing to check is the engine temperature gauge although the command for aircon should overide this. What area are you in as there are members on here that will help free

 

I'll see if I can get at the fan tomorrow and apply 12V directly.  Looking at the Citroen service manuals (£10 from ebay :) ), getting to the fan doesn't seem *too* tricky, but I'm a total novice when it comes to servicing/fixing cars.  I've recently thought I should try and have a go a bit more though.  I spent over £1000 after an injector developed a fault a few months ago :(

It's interesting and encouraging you say there is an issue with the relays.  Looking at the exploded diagrams, I can see that there is a replacement part (RP 6546 XF) that replaces the original (6545 N5).  Fingers crossed, it's the relay.  A bit of googling for the cost of the fan and so far I've seen the figure £400 :(  http://uk.picclick.com/PEUGEOT-407-CITROEN-C5-C6-COOLING-RADIATOR-FAN-370795588764.html

The relay, on the other hand, is *much* cheaper. http://www.citroen-accessories.com/home/87737-rp-6545-xf.html

 

I'm now fully equipped with a Lexia and the Citroen documentation (some of it seems quite good, some of it is useless), now I just need a bit more confidence.  It's nice to know there are people who might be able to help out.  I'm in Frome, Somerset.

 

Thanks,

Alex

[paul.h]

The relay is £13.44 from this site http://www.citroencarparts.net/?s=6545XF so probably the same from your local dealer and the fan £323. You are most likely to need to order the bits from your dealer and being a bank holiday if ordered Tuesday you would get them Wednesday if ordered as vehicle off road or Thursday - by not being in too much of a hurry, I have found my dealer can get the parts at a lower cost and can give a discount for regular customers so worth asking.

[coastline taxis]

if the fan is knackerd itl be the bushes ( As there really is nothing else in there to fail) and any auto electrition can supply and change for £30ish pounds

[alexjfisher]

Still no joy :(

 

I tried some DIY investigations at the weekend, but failed miserably to even get the engine under tray off before it started tipping it down.  I think I removed all the screws/bolts, but it just didn't want to come out.  Afraid of breaking anything and with the weather/light deteriorating, I gave in.

 

As my MOT was due, I had my local independent mechanic have a look.  He replaced the maroon relay, but it still doesn't work.  He's not prepared to spend any more time on it has he says as far as he's concerned it could be anything (wiring, BSI, relays, fuses etc).  Which is fair enough, considering the time he's already spent without charging me.

 

 

 but anyway there was a problem with the relays on the cooling fan corroding there next to the radiator on the suport panel under a black cover. 

 

Hi coastline taxis! Are you saying that there are relays other than the maroon one I replaced?  Peering in through the bonnet release catch hole, I can possibly seem some sort of black oblong box mounted vertically and to the right of the fan.  Is it in here you think the problem might be?  If so, is it something that can be repaired?  If I've got to replace something, is it available separately, or does it come with the replacement fan part number?

 

Many thanks,

Alex

[coastline taxis]

yes its inside that box that you can see.when weve removed the cover sometimes the wires are just corroded to hell and other times its the relays that just fall apart. If its the relays its a quick fix if its the wiring then youl need to replace the harness its not expensive just a bit fiddly. its easier to remove the front bumper and grill which gives you loads of space to work on it and leaves the radiator and fan and wires in place.  And if memory is working i think its the top green relay that goes

[alexjfisher]

Thanks!  I've enlisted the help of a friend and we're going to have another go at fixing it this weekend.  Is taking the bumper off an X7 model straightforward?  I've got a service documentation CD off ebay, so I'm sure instructions are in there somewhere but there's probably stuff they don't say too.

 

Do you know the part numbers for the relays and/or wiring that might need to be replaced?  I can't seem to find them in the service docs.

Many thanks,

Alex

[alexjfisher]

Some progress made.  Relay box doesn't contain any other relays, just the maroon one my garage already tried replacing and the wiring *looks* fine.  But, I was able to remove the fan from the car.  It's got two connectors, each with two wires.  The larger connector I assume is power and the smaller one speed of rotation sensor maybe??

Putting 12V across the two terminals in the larger connector, doesn't do anything, so I guess it's the fan itself that is knackered?  Or is the smaller connector for controlling some relay inside the fan itself?

 

I've put out a request on findapart and am waiting with fingers crossed.

[paul.h]

A look at a wiring diagram in the Review Technique manual for the C5 (X7) shows the fan has a supply through the relay (maroon) and maxi fuse 1, an earth and then 2 wires from/to the ecu. The relay also has another supply through fuse 21 and fuse 1 and relay 1 in the engine fuse box. So it looks as if you may also need to put a supply across the other 2 wires to get the fan to run - it looks as if the ecu puts a supply through the fan to a control of some sort (just shown as a triangle in a box) that then pulls in the maroon relay. Relay 1 in the engine fuse box needs a supply from the engine ecu to pull in the 12 volt fuse 1/21 supply to the maroon relay.

 

It may also be worth checking the earth for the fan and there is a permanent 12 volt supply (from MF1) both to the maroon relay.

[qman3428]

If you break any of the floor fastenings you can replace them with electrical tie wraps, much esier to fit!

[coastline taxis]

Check the wiring were it comes of the radiator support panel and goes into the relay box right on the bend. Also pull the relay and check it yourself