Fitting air conditioning in an old diesel BX

rmattila · Post by **rmattila** » Sat Jul 09, 2011 11:17 am

I came across the air conditioning system parts of a BX that was on its way to the scrappers. Never had a BX with air conditioning - never even seen one here in cold Finland - and was not able to do the dismantling of the parts by myself, so now I'm in possession of a few boxes full of parts that should somehow in the future find their new home in the black Van.

Any information regarding the installation and modifications required for fitting the aircon parts is greatly appreciated. Especially the mounting arrangement of the compressor would be of interest.

toddao · Post by **toddao** » Sun Jul 10, 2011 12:07 pm

Mat Fenwick is your man on this one - he fitted A/C to his diesel estate. Also Vanny I think did the same on his 16v and he also knows a bit about air-conditioning.
I've also got the boxes of bits which I removed myself from a GTI - doesn't mean that I can remember where they all go!

Jaba · Post by **Jaba** » Sun Jul 10, 2011 11:18 pm

Its not a difficult job at all really but does need a bit of planning first.
Are you sure you have all the parts needed. These include an alloy sump with compressor mountings and the central part of the dashboard which contains the heater matrix and the required aircon evaporator and the two blower motors and two air recirculation flaps which may need two sizeable holes cut in the bulkhead if they are not there already covered over with blanking plates.
I have a wiring diagram should you need it.

Strangely there has never been a write up on how to instal aircon from scratch but if you do a search you will find plenty of info on how to do it.
Beware though, it might put you off starting.

rmattila · Post by **rmattila** » Mon Jul 11, 2011 8:06 am

I've not yet completely sorted out the system in my head. My first impression is that I probably have all parts besides the mysterious "A/C type sump" I've seen mentioned to be needed. There are a couple of pulleys and an aluminium bracket holding one of them, but the mounting of the compressor is really the biggest mystery for me.

I have a number of broken engines with intact sumps, which the required A/C one could probably be made from, but I would need to see an assembled system first to get an idea how it's supposed to be fixed. And where is the power taken from in the engine? Is an extra pulley fixed on top of the alternator one or what..?

Jaba · Post by **Jaba** » Mon Jul 11, 2011 8:36 am

You can see a pic of a sump showing the compressor mounting lugs here:
http://cgi.ebay.co.uk/Citroen-BX-16v-Pe ... 3a67d17c9f

The a/c is driven by a longer alternator belt with or without those extra pulleys that you mention which are not really necessary.

rmattila · Post by **rmattila** » Mon Jul 11, 2011 8:47 am

Jaba wrote:You can see a pic of a sump showing the compressor mounting lugs here:
http://cgi.ebay.co.uk/Citroën-BX-16v-Pe ... 3a67d17c9f

Thanks, that clarifies a lot. Does not seem impossible to weld the necessary fittings and supports to an ordinary sump.

The a/c is driven by a longer alternator belt with or without those extra pulleys that you mention which are not really necessary.

This is what I initially thought too, but got doubtful on realizing that the pulleys included in the A/C system are ordinary V belt pulleys, whereas the alternator runs on a multi-rib (poly-V) belt such as that one.

toddao · Post by **toddao** » Mon Jul 11, 2011 10:48 am

Hello Jaba - I forgot you were an A/C man too. Also installed afterwards?

Post by **mat_fenwick** » Mon Jul 11, 2011 7:16 pm

rmattila wrote:Thanks, that clarifies a lot. Does not seem impossible to weld the necessary fittings and supports to an ordinary sump.

I suspect the lack of rigidity from a steel sump may be an issue, but I'm sure someone of your ingenuity can come up with a solution.

rmattila wrote:the pulleys included in the A/C system are ordinary V belt pulleys

Are you sure the system is from a BX? The factory BX systems use the same multi-grooved belt as the alternator, but obviously aftermarket systems may not. Where the switches in the dash above the heater dials?

rmattila · Post by **rmattila** » Mon Jul 11, 2011 9:02 pm

mat_fenwick wrote:I suspect the lack of rigidity from a steel sump may be an issue

Yes, I thought of that - some kind of additional support structure is certainly needed, not just the mounting points on the thin steel. But there's plenty of room for adding that support around the sump.

Are you sure the system is from a BX?

Well, the guy I got it from has broken more than his share of BX's, so I'm pretty sure that's what he removed it from - however I have no idea of the origins of the equipment. That's what the parts (excluding the condensor) look like - I guess I still need to sleep a couple of nights to figure out how they're supposet to be fitted (and then end up fitting them on the coldest day of next February.

)

Post by **mat_fenwick** » Mon Jul 11, 2011 10:16 pm

Ah. Looking at the switch it seems to be the one fitted to the centre console rather than the 'factory' location above the 3 heater dials. I believe that the switch was fitted in the console on aftermarket installations (or as a dealer fitted (rather than factory fitted) option. The other bits look significantly different to my system, and others I have seen.

Based on that I would simply mount the compressor in any suitable location using engineering sense, rather than trying to emulate the factory positioning. At the end of the day all it needs to do is turn at an appropriate speed.

rmattila · Post by **rmattila** » Mon Jul 11, 2011 10:29 pm

mat_fenwick wrote:Ah. Looking at the switch it seems to be the one fitted to the centre console rather than the 'factory' location above the 3 heater dials. I believe that the switch was fitted in the console on aftermarket installations (or as a dealer fitted (rather than factory fitted) option. The other bits look significantly different to my system, and others I have seen.

Based on that I would simply mount the compressor in any suitable location using engineering sense, rather than trying to emulate the factory positioning. At the end of the day all it needs to do is turn at an appropriate speed.

Your suggestion is very close to the lines I've been thinking about: all those pulleys and brackets seem a very complex way of accomplishing a simple task - and I really have no idea where that large alloy bit with the pulley would fit on a BX engine. .

Unless I suddenly see the light and realize the meaning of the parts in the picture, I guess I'll just machine out a multi-groove pulley for the compressor, work out a sufficiently rigid sump fixing, and go along the straightforward route.

However, as I'm pretty sure those parts really came from a BX Van (where they have been installed as an aftermarket system), my engineering instincts tell me there really should be a way of putting them back together without having to use machine tools..

Jaba · Post by **Jaba** » Wed Jul 13, 2011 12:08 am

Looking at the pics that looks like the after market aircon supplied by Diavia. But using a V belt and pulleys instead of a poly v belt makes me wonder if it did come from a BX. It must have had an alternator with a v pulley as well.
But either way the Diavia system is a pretty poor design compared to the factory original. I had to completely rewire mine to get it to work properly and am going to convert it to the standard switching sometime in the future to get the benefit of being able to adjust the amount of cooling with the slider switch, which you will not have.

Still even that aircon system is better than none at all of course.

rmattila · Post by **rmattila** » Wed Jul 13, 2011 7:47 am

The blower parts are definitely from a BX, and the system was removed from a BX Van a few weeks ago (in northern Finland, so I was unable to take part in that fun myself). However, I have no information on what kind on engine that Van had - there's of course a possibility that it has gone through some innovative engine change..

But I get from your replies that all BX A/C systems have been mounted by the alternator (=powered by the crankshaft pulley) and not by the HP pump (=powered by the camshaft pulley). So it seems most straightforward to fix a chunk of waste steel on the lathe chuck, turn a suitable poly V pulley and start from there..

As to the wiring, I have no experience on any A/C systems (not needed for too many days per year up here). I presume the epansion valve is operated based on the need for cooling (=ideally by a thermostat), but what information drives the compressor clutch? I would guess there's a pressure switch somewhere..?

Anyway, the first thing to do is to get the hardware in place and think of the instrumentation after that..

toddao · Post by **toddao** » Wed Jul 13, 2011 7:47 am

I think the Mk.1 BXs also had the A/C switched from the central consule.

Jaba · Post by **Jaba** » Wed Jul 13, 2011 8:35 am

OK there is obviously no need to make a crankshaft or alternator pulley its just the compressor you are talking about.
Have a look at this pulley. It has an electric clutch fitted within the pulley itself so may be quite complicated to replicate.