CX aircon.

Post your Cit/Peu/Ren air conditioning queries or advice.

Moderator: RichardW

tomsheppard
Posts: 1801
Joined: 19 Dec 2002, 15:46
Location: United Kingdom
My Cars:

CX aircon.

Post by tomsheppard » 03 Feb 2005, 03:30

Having driven the CX for the last 500 miles and felt it come back to life, even if I can't source an air filter for it, I am slowly warming to it and WBM loves the darn thing. THe air conditioning is clearly working as the compressor and the TX valve are nicely frosted. Not a lot of cold air comes out though. THe car is fitted with a climate control system which when it comes to ventilation
gives me an understanding of the term Molecular Seive.
Honestly, it can't be this bad? I am guessing that the heater (Which works) is an air blend type without a valve and that air is directed by flaps which also seem to move (The motor drives the one in the dash center ok. The fan motor runs at three speeds
slow, not so quick and less fast than that and the system has a recirculator motor which runs ok BUT doesn't run the fan fast!?
Plan A: separate switch to recirc motor to use maximum fan with aircon.
Plan B: Ask if the evap could be blocked with birds' nests and the like over 20 years, impeding the flow. If it is, (And I won't be satisfied until I know...)Then I'll have to remove bits of heater to get to it and I haven't a clue where to start! It is a mark one diesel.Does anybody know how much taking apart I'll need to do?
While it is out, I'll try to clean up the fan which should help a bit.
Plan C: Unsightly snorkel on bonnet top. I've seen them on some French examples. Do they work?
0x

bernie
Posts: 882
Joined: 10 Apr 2001, 02:25
Location: Southampton United Kingdom
My Cars:

Post by bernie » 03 Feb 2005, 05:24

Tom
Have you tried Haynes, unfortunatly it does not cover diesel but its better than nought.
Details below, the library will get you a copy
Citroën CX Petrol (75 - 88) up to F


CX 2000, CX 2200, CX 2400, CX 25 Saloon and Estate, 75 - 88, up to F
2.0 litre (1985cc), 2.2 litre (2175cc), 2.3 litre (2347cc) and 2.5 litre (2500cc) ohv, inc. Turbo

Does NOT cover Diesel models
Does NOT cover 2.0 litre (1995cc) or 2.2 litre (2165cc) ohc engines fitted to CX 20 and CX 22, Athena and some Reflex models

Book No: 0528
ISBN: 1 85010 449 2
List price: £17.99
Web price: £15.99
Availability: In Stock
0x

alan s
RIP 2010
Posts: 2542
Joined: 26 Jan 2001, 16:53
Location: Australia
My Cars:
x 4

Post by alan s » 03 Feb 2005, 08:50

It apparently is possible to make the air/con work on a CX series one, but hoo boy, this is a challenge that I have so far avoided.
Take a look at the design of the air intake; if ever there was a case for not drinking at work, this has to be it!
Your fresh air comes in via the vent on top of the bonnet. Under that there is a periscope that fits hard up against it; well it used to be, so what happens now is that the rubber seal between the periscope and the bonnet has long gone and is allowing the hot air from under the bonnet to run straight down it. I used a piece of foam carpet underlay, spot glued it to the underside of the bonnet below the vent and closed the bonnet for a couple of minutes. Raise the bonnet and cut to shape so that it forms a seal and that's half of the problem (from this source) gone.
Secondly, have you got any idea how hot that black plastic periscope gets? Where does all the heat go?? Yep, driven down the hole and across the coil by the fresh air. The CX Rally cars of the 70s had insulation wrapped around the outside of that periscope obviously for that reason; to try to keep it cooler.
Next problem. Stopping the heat from the matrix bleeding into the car and causing excess load on the air/con system.
Shane has written that up pretty well complete with pics here:
http://www.aussiefrogs.com/shane/cx2400 ... aterl.html
There is an insulated panel that gets rotten and falls apart and valves and flaps that don't operate 100%. That sorted will get you in with a fighting chance. Another thing used by them too, is to fit a tap to the line supplying the hot coolant to the matrix and cutting off the circulation.
One of my sons fitted a large fully aluminium radiator on his as well as lining the entire floor and firewall with a rubber insulation about 4mm thick, this helped a lot too. Be sure there are heat baffles above the muffler area to break the direct heat between the muffler and the floor of the car as on petrol cars anyway, the front muffler sits almost directly below the evaporator and radiates enough heat to almost absorb all the capacity of the air/con system.
Check the condensor; the early ones in Australia were fitted in Europe I believe and possibly worked well in Finland in December. They used to be about half the size of the radiator and had only one fan operating on them (which was all they had space for) but a second fan worked on the actual balance of the radiator; bloody stupid idea.
You need a condensor that goes the full width of the radiator, 2 fans and I have been told that a 3 speed fan switch is available so that the temperature of the condensor and radiator are kept constantly under control by having the fans running at a slower speed when the compressor cuts out.
Basically summing up, it means get rid of all vagrant ambient temp air, any heat bleeds from outside sources (ie) mufflers, matrix etc, insulate wherever possible, increase capacity to dump heat extracted from the system via larger condensor and fans.
I have been told they can be made work, but in all honesty, it was too much for me, so much so that I used to rip the entire air/con systems out of my CXs to get better access under the bonnet and this in turn reduced the temp which when combined with the stopping off the heat sources, made them reasonably comfortabe for a non air conditioned car.
Alan S
0x

tomsheppard
Posts: 1801
Joined: 19 Dec 2002, 15:46
Location: United Kingdom
My Cars:

Post by tomsheppard » 04 Feb 2005, 20:33

OK, so it is gonna be a challenge, huh? Something to get my teeth into while I look for a Turbo2 engine.
0x

alan s
RIP 2010
Posts: 2542
Joined: 26 Jan 2001, 16:53
Location: Australia
My Cars:
x 4

Post by alan s » 05 Feb 2005, 02:44

Tom,
Another point that dawned on me (in the wee small hours) was that the original CX condensors were built very much like a heater matrix.
By that I mean that through the fins ran tubes about 3/8' diameter with a series of elbows at the ends. The condensors on BX by contrast are a series of elongated tubes approx 21mm wide that snakes the full height of the condensor and would give a much better flow of gas which at that stage is in the process of returning to liquid as it condenses and as a result, I personally feel that this will carry a much greater capacity of the gas and providing the air flow and finned area were up to the job be much more efficient that the original set up which in reality was designed, built and installed in the fairly early days of car air/conditioning.
Out here so presumably over your way, it is possible to get custom built condensors or even just the actual coil to which the existing mountings are then pop rivetted.
Just a thought, but worthy of consideration don't you think?
Alan S
0x

tomsheppard
Posts: 1801
Joined: 19 Dec 2002, 15:46
Location: United Kingdom
My Cars:

Post by tomsheppard » 05 Feb 2005, 03:09

Have you tried to get hold of a BX condenser these days Alan? I think I'd probably look for one from a Scooby on your advice. I think that the main problem is one of airflow. there's plaenty of cold around but it isn't getting to me. The other side of the compressor is only slightly warm (low ambient here and now) so the system is working. I'll have to look at the incoming airbox and I may even louvre the bonnet to get some of the heat soak from the turbo away.
0x

alan s
RIP 2010
Posts: 2542
Joined: 26 Jan 2001, 16:53
Location: Australia
My Cars:
x 4

Post by alan s » 05 Feb 2005, 04:19

Tom,
It sounds as though you're not getting the air load over the evaporator.
Did you see my final posting on the retro fit? It sounds as though you may have a similar problem as the one he had; plenty of air flying around in there but messy like a fan blade being assabout. Worth a check. His fans will now mess his hair up at high speed; that's what you call circulation.
The Suby condensor incidentally needs different fittings on it as it comes with flare ones but I couldn;'t imagine that would be too difficult a task.
BX condensors are a stupid price that can't be justified, but I wouldn't go looking for a BX condensor for a CX. There'd be plenty other less expensive ones around I dare say. Do a measure on what will fit in there and I'll take a look at my parts book and see if there's anything compatable.
Alan S[8D]
0x

tomsheppard
Posts: 1801
Joined: 19 Dec 2002, 15:46
Location: United Kingdom
My Cars:

Post by tomsheppard » 05 Feb 2005, 16:25

Yep, that's how I see it, the evap has probably been clogged with 20 years of dust and could do with a good hosing through and the fan motor will almost certainly welcome a strip and clean if experience is anything to go by. I've got a full witth condenser on this car but as yet, I don't regard that as the problem. As you say, there just isn't enough air getting into the cabin.
0x

ghostrider
Posts: 360
Joined: 05 Jan 2002, 02:10
Location: United Kingdom
My Cars:

Post by ghostrider » 06 Feb 2005, 02:42

Tom I have a Mk1 Official Cit Workshop manaul I'll scan and E-mail you any relevant bits if you like, I fitted a scoop over the intake grill on the bonnet of my non air con CX to try and improve the air flow which is abysmal, even if all the relevant bits of rubber are in place and the fan is working OK, It was certainly the weak point of CXs, to stop the heater matrix leaking heat into the passenger compartment I simply put a 22mm service valve on the inlet pie to the heater in the engine compartment, so a simple turn of a screwdriver turned the supply on or off.
best regards Pete
________
ARAB RECIPES
Last edited by ghostrider on 22 Feb 2011, 06:57, edited 1 time in total.
0x

tomsheppard
Posts: 1801
Joined: 19 Dec 2002, 15:46
Location: United Kingdom
My Cars:

Post by tomsheppard » 06 Feb 2005, 02:50

Thanks Pete. I'll take you up on that.
Certainly the heater works well enough but the climate control needs the tender mercies of a competent engineer to frighten it into behaving! the idea of a valve,(Possibly solenoid operated, would help but a beefier fan motor, secondary air inlet into the plenum chamber and a good clean of the evap will be the first things to try.
Did the scoop work?
0x

alan s
RIP 2010
Posts: 2542
Joined: 26 Jan 2001, 16:53
Location: Australia
My Cars:
x 4

Post by alan s » 06 Feb 2005, 03:15

The scoops work to a point, but usually operate better on cooler days as all they do is send cooler air down the intake vent at a greater velocity and in the case of trying to air/con the car this is counterproductive.
Alan S
0x

tomsheppard
Posts: 1801
Joined: 19 Dec 2002, 15:46
Location: United Kingdom
My Cars:

Post by tomsheppard » 06 Feb 2005, 03:38

Fair enough. Do you have that deja vu feeling again, Alan? At least this time the system is fully assembled with only Citroen's development engineering to do for them. I wonder if it is a hangover from making so many air cooled cars that they tend to make such a hash of heating and ventilation on the rest?
0x

ghostrider
Posts: 360
Joined: 05 Jan 2002, 02:10
Location: United Kingdom
My Cars:

Post by ghostrider » 06 Feb 2005, 06:07

Tom I'll have a look tomorrow to see what there is, the scoop worked to an extent but it wasn't until I dismantled the whole thing to replace the heater matrix that I realised that the main problem is that the air when set to cold follows a very convoluted route, if the evaporator is placed in that air flow, with the way that a matrix kills the air velocity I can imagine that very little air would emerge from any of the vents . I also wonder whether a linear rather than an axial fan would be better.
Solenoid op valve would be a nice touch, a caravan equipment shop or marine chandler should be a good source of a 12v version
I also seem to remember seeing a mod that a French owner used with air intakes feeding through flexible tube to the base of the air intake stack, with a fan in each one although I have a feeling that it was a Mk II with plastic bumpers and the intakes were in place of the low level fog lights.
I take Alan's point about just directing more air into the car, which in Aus is likely to be at least Hot [:D], whereas over here it is mostly cold and damp [:D][:D] [:D] The only thing is I don't remeber the air flow being any better on recirculate, so you are still left with the problem of actually getting the air in the car across the evaporater to cool it. I always felt that the only real solution was to bring the cold air direct into the car somehow, but I've never quite figured out how to do it so it looked any good.
You may well be right about the air cooled engine angle, my GS/GSA used to pump loads of hot air in, assuming that there were no holes in the flexibles, and the face level vents either side drew cold air straight from the outside a rate of knots, which given the UK climate was always just about enough to make the inside tolerable on a hot day in the UK [:D] [:D] [:D] [:D] [:D] [:D] Certainly the CX was a big disappointment from that point of view, but hey what GS ever did 0-60 in less than 7 secs ? [:D] [:D] [:D] [:D] [:D] [:D] [:D] [:D]
Pete
________
MEDICAL MARIJUANA
Last edited by ghostrider on 22 Feb 2011, 06:57, edited 1 time in total.
0x

tomsheppard
Posts: 1801
Joined: 19 Dec 2002, 15:46
Location: United Kingdom
My Cars:

Post by tomsheppard » 06 Feb 2005, 16:45

Yes! An auxiliary plenum with a fan stuck low down! Brilliant Holmes! THanks for the tip re chandlers as well. I think that I'm starting to get a real feel for this challenge.
0x

alan s
RIP 2010
Posts: 2542
Joined: 26 Jan 2001, 16:53
Location: Australia
My Cars:
x 4

Post by alan s » 06 Feb 2005, 17:03

Perhaps we are beginning to understand why they ran 2 fans on the BX system.
Alan S
0x