CX air-conditioning -- or fitting of

[DoubleChevron]

Hi Guys,

I'm after some ideas here.

while the motor is out of the car, I will plan on how I should fit air conditioning. The rear evaporator is obvious. However the front air-con is hopeless.

This car has no factory fitted air-con at all. That means there is no re-circulation flaps or ducting on the bher heating box (which is possibly why is always blows a very gentle breeze of ambient rather than hot air through the vents ?).

Here's my initial thoughts.

--grab air from the cutout where the recirculation is usually hooked up (I'm assuming there is a blanking plate in the firwall).
--Where the spare wheel sits, mount a box with the evaporator, TX valve, and nice big strong fan in it. Run the cold air output from the fan through to under the dash where it will be hooked up to the two side vents on the dash (which generally have no air-flow due to the very poor amount of air the existing fan uses).

In this way the "new" fan in the box under the bonnet could blast huge quantities of air through the two outer dash vents in the car, and for fresh air you could leave the other vents open with the heater fan off for a tiny gentle breeze of ambient temp fresh air through the other vents.

This would bypass the god awful heater box setup, allow decent air flow into the car, and give very easy access to the evaporator and TX valve in the event the air-con needs fixing. The temperature control inside the car would still work as you could just turn the air-con on at very low fan speeds, then set the temperature with the heater control, the heater would then vary itself to give the desired temperature inside the car (which is exactly how the existing temp control works, only through the existing vents inside the car).

Does anyone have any ideas on fan/air-con boxes or insulated ducting that could be used ? This will most likely be my winter project for next year

thanks
Shane.

[chris]

Why not grab the variable-thermistor setup out of a BX? Then the A/C pump only runs when it needs to, and you reduce the drain on the engine rather than cooling down air to reheat it with heater.

Would it be worth your while to try and get a complete Series Two evaporator assembly to fit inside the dash? There should be a few available from New Zealand cars, if you talk to the right people.

Chris

[DoubleChevron]

Originally Posted by chris

Why not grab the variable-thermistor setup out of a BX? Then the A/C pump only runs when it needs to, and you reduce the drain on the engine rather than cooling down air to reheat it with heater.

Would it be worth your while to try and get a complete Series Two evaporator assembly to fit inside the dash? There should be a few available from New Zealand cars, if you talk to the right people.

Chris

To put it bluntly, the factory air-con is bloody useless... It would be pointless fitting the indash air-con. The evaportor could be -20degrees... But you can't get any air through the dash vents to make a difference. This way we bypass the hopeless bher ventilation box inside the car.

The air-con pump, rather than driving it from the water pump (dumb), I'm thinking running just one belt over to the water pump/alternator (remember CX's run twin belts) and using the second cam pulley to turn the air-con compressor ?? Mounting it maybe back towards where the spare wheel usually is ?? Not sure, I'd need to plan and investigate.

Anything I do will be reversable to put the car back, without cutting any holes (excpet for the one hose into the car to carry the cold air to the dash vents).

You have to try the ventilation in this car to understand... All the vents closed, fan howling full bore through just the centre dash vent, and you can just feel it on your face if you guide the vents at your face

seeya,
Shane L.

[chris]

Actually, what am I talking about. Aren't the Aussie 2.5s Series 2 cars? With A/C?

Chris

EDIT: Oh, never mind then.

[Greg C]

Hi Shane

a thoughts

1. Recirculation - I am pretty sure all CXs got this, the motor driven flap under the expansion bottle. I would get that going and use it

2. Another evap outside the normal air trunking. Not a bad idea but I would still blow air through the normal heater box because in mid season you will need to add a bit of heat I think. Also if you are going to this sort of trouble you will make a hot water cutoff valve and have it so the hot water is shutoff when the temp lever is all the way back

3. Further to 3 I think of it as kind of supercharging the normal system. That is one thing wrong with the CX, the amount of air flow through the front system very poor compared to say a Xantia.

4. Where is this extra evap going to pick up air. I would strongly suggest cutting into the existing trunking upstream of the existing fan, through the extra evap, extra fan then back into the extisting system. That way you can recirculate everything on really hot days and get good airflow.

5. Other things to do would be pull the heater box down and fit new foam to the flaps and then adjust so you can completely close off the flow through the heater when you don't wan't it

6. Use a space saver spare to give yourself more room

7. A simpler approach might be to shoe horn a Xantia fan in place of the normal CX fan. Simpler and it should make a big improvement.

Greg

[DoubleChevron]

Originally Posted by Greg C

Hi Shane

a thoughts

1. Recirculation - I am pretty sure all CXs got this, the motor driven flap under the expansion bottle. I would get that going and use it

2. Another evap outside the normal air trunking. Not a bad idea but I would still blow air through the normal heater box because in mid season you will need to add a bit of heat I think. Also if you are going to this sort of trouble you will make a hot water cutoff valve and have it so the hot water is shutoff when the temp lever is all the way back

3. Further to 3 I think of it as kind of supercharging the normal system. That is one thing wrong with the CX, the amount of air flow through the front system very poor compared to say a Xantia.

4. Where is this extra evap going to pick up air. I would strongly suggest cutting into the existing trunking upstream of the existing fan, through the extra evap, extra fan then back into the extisting system. That way you can recirculate everything on really hot days and get good airflow.

5. Other things to do would be pull the heater box down and fit new foam to the flaps and then adjust so you can completely close off the flow through the heater when you don't wan't it

6. Use a space saver spare to give yourself more room

7. A simpler approach might be to shoe horn a Xantia fan in place of the normal CX fan. Simpler and it should make a big improvement.

Greg

Hi Greg,

you know how CX2200's have the most air-flow, then CX2400 were worst ... Well the Series II is even worst again... It's simply hopeless. Chris stewart over in perth even tried an air blower taped to the intake on the bonnet, little 2stoke engine screaming full bore blasting air through the vents .... To find exactly the same air-flow inside as the fans on high ie: given the inlet and outlet restrictions, the existing fans are already running at the fastest speed possible. I've also heard of other poeple on the internet exitedly fitting different fans ...... To either find no improvment, or no follow up to the fans being fitted (most likely due to the dissapointment that all there work made no difference).

The heater box in this car works perfectly, even when it's 44degrees outside, I only get a (verry gentle) breeze of ambient NOT HOT air into the car.

There is no air recirculation ducting on the bher heater unit. Rather there is a button inside the car that rather than puts the air onto recirculate, shuts everything off to stop airflow. I'll take some piccies to show you.

I still think, a small box where the spare wheel sits, everaporator/tx valve in this box with a nice big fan, drawing air from where the recirculation ducting usually is, and blowing through the outer dash vents (that don't have any measurable air-flow at the moment) would work incredibly well. Imagine the air-flow you could get by by-passing the bher heater box. I'm thinking the vents would be like the early BX16trs we had, the air so bloody cold you get an instant headache by aiming them air stream at your face !

seeya,
Shane L.

[chris]

The thing about the airconditioned BXes is that they're set up to flow a lot more air through the ENTIRE system than the non-AC cars. Come to think of it, you've probably never seen a non-AC BX. They only have one cabin ventilation fan. The diference between my car with both those big fans running full bore and the non-AC cars my family in NZ have is huge. I don't really miss not having the AC connected in our car, but the non-AC cars are quite hot...

My point (I do have one!) that you're probably fighting a losing battle with the CX unless you can do something about that heater box and air ducting. Can you cut the shrouding or open out the ducting somehow? I really doubt that those two little side vents are going to cut it. Consider that the BX has FOUR of those mid-level vents, plus the floor-level ones, all flowing a lot of air.

Chris

[DoubleChevron]

Originally Posted by chris

The thing about the airconditioned BXes is that they're set up to flow a lot more air through the ENTIRE system than the non-AC cars. Come to think of it, you've probably never seen a non-AC BX. They only have one cabin ventilation fan. The diference between my car with both those big fans running full bore and the non-AC cars my family in NZ have is huge. I don't really miss not having the AC connected in our car, but the non-AC cars are quite hot...

My point (I do have one!) that you're probably fighting a losing battle with the CX unless you can do something about that heater box and air ducting. Can you cut the shrouding or open out the ducting somehow? I really doubt that those two little side vents are going to cut it. Consider that the BX has FOUR of those mid-level vents, plus the floor-level ones, all flowing a lot of air.

Chris

Hi Chris,

I'll do some testing, but I'm not going to butcher the existing fan setup in the car. I want anything I've done to be "reversable" if needed. Remember we'll also have cold air blasting from four vents on the back parcel shelf too Trust me, two vents blasting lots of air is vastly prefable to 6vents moving nothing Plus by disconnecting the outer two vents, we may increase the airflow to the centre vents for heating purposes in winter. The biggest issue IMO of using just the outer vents for air-con, is you can't then use the air-con to demist the windscreen in winter.

Greg, here's the side of the heater box where the recirculation usually is. The engine driven flap is still there, but it only closes off air-flow, it doesn't re-direct it.



This is the existing air pickup tunnel that clamps closed against the thick rubber on the back of the bonnet:



The space you could use for a fan box where the spare wheel sits.



seeya,
Shane L.

[robmac]

Originally Posted by DoubleChevron

Hi Guys,

I'm after some ideas here.

while the motor is out of the car, I will plan on how I should fit air conditioning. The rear evaporator is obvious. However the front air-con is hopeless.

This car has no factory fitted air-con at all. That means there is no re-circulation flaps or ducting on the bher heating box (which is possibly why is always blows a very gentle breeze of ambient rather than hot air through the vents ?).

Here's my initial thoughts.

--grab air from the cutout where the recirculation is usually hooked up (I'm assuming there is a blanking plate in the firwall).
--Where the spare wheel sits, mount a box with the evaporator, TX valve, and nice big strong fan in it. Run the cold air output from the fan through to under the dash where it will be hooked up to the two side vents on the dash (which generally have no air-flow due to the very poor amount of air the existing fan uses).

In this way the "new" fan in the box under the bonnet could blast huge quantities of air through the two outer dash vents in the car, and for fresh air you could leave the other vents open with the heater fan off for a tiny gentle breeze of ambient temp fresh air through the other vents.

This would bypass the god awful heater box setup, allow decent air flow into the car, and give very easy access to the evaporator and TX valve in the event the air-con needs fixing. The temperature control inside the car would still work as you could just turn the air-con on at very low fan speeds, then set the temperature with the heater control, the heater would then vary itself to give the desired temperature inside the car (which is exactly how the existing temp control works, only through the existing vents inside the car).

Does anyone have any ideas on fan/air-con boxes or insulated ducting that could be used ? This will most likely be my winter project for next year

thanks
Shane.

Greetings Shane,

Let open by saying any after market aircon is PITA to install. Made worse by the fact you are building from made up bits and not installing a kit.

The compressor mount and drive is the easy part- source the parts off a another Cit.

Likewise the condenser. Fit the biggest unit you can fit in and fit additional fan to get lots of air through the coil. FYI condensers work OK when horizontal, so if you can fit one under car that is OK. Lots of airflow and fan needed on a horizontal unit tho.

Plumbing is too much of a problem- it may be a trip to Enzed or Hose Doctor. Don't use worm drive clips !

The evaporator is always the problem.

An under dash unit like the Mark V (five) units are the best for cooling -air straight off the coil straight into your face. An under dash probably would not fit a Cit.

If I were you I would go trawling the wreckers and look for a fan and evaporator off a Jap car. Toyota or Honda (nippondenso product). The unit should be off a BIG car . In operation you want as much fan speed and airflow as possible. Also grab the dash control switches, thermostat and hoses. The ND evaporators use a thermistor, but you can easily fit a mechanical thermostat

You may need to build a box for it and do some ducting. Use at least 150mm diameter duct for suction and keep it short as possible, or use two smaller ducts. For pressure side of the fan use at least 100mm. The black spiral ducting is the go, to insulate it, get some fibre glass insulatation off the house heating duct. You can form an outer sheath using concrete membrane plastic sheet and tape it all up with grey duct tape.

Don't forget the condensate drain hose and remember it must work with the car parked nose up and nose down on steep inclines without flooding inside the car. 10MM minimum diameter

I think you are on the right track with a separate system to the car heater/ventilator.

You need to be a brave man to tackle an install like this !

[DoubleChevron]

Originally Posted by robmac

Greetings Shane,

Let open by saying any after market aircon is PITA to install. Made worse by the fact you are building from made up bits and not installing a kit.

The compressor mount and drive is the easy part- source the parts off a another Cit.

Likewise the condenser. Fit the biggest unit you can fit in and fit additional fan to get lots of air through the coil. FYI condensers work OK when horizontal, so if you can fit one under car that is OK. Lots of airflow and fan needed on a horizontal unit tho.

Plumbing is too much of a problem- it may be a trip to Enzed or Hose Doctor. Don't use worm drive clips !

The evaporator is always the problem.

An under dash unit like the Mark V (five) units are the best for cooling -air straight off the coil straight into your face. An under dash probably would not fit a Cit.

If I were you I would go trawling the wreckers and look for a fan and evaporator off a Jap car. Toyota or Honda (nippondenso product). The unit should be off a BIG car . In operation you want as much fan speed and airflow as possible. Also grab the dash control switches, thermostat and hoses. The ND evaporators use a thermistor, but you can easily fit a mechanical thermostat

You may need to build a box for it and do some ducting. Use at least 150mm diameter duct for suction and keep it short as possible, or use two smaller ducts. For pressure side of the fan use at least 100mm. The black spiral ducting is the go, to insulate it, get some fibre glass insulatation off the house heating duct. You can form an outer sheath using concrete membrane plastic sheet and tape it all up with grey duct tape.

Don't forget the condensate drain hose and remember it must work with the car parked nose up and nose down on steep inclines without flooding inside the car. 10MM minimum diameter

I think you are on the right track with a separate system to the car heater/ventilator.

You need to be a brave man to tackle an install like this !

Hmm,

good points. I do have a '82 CX2400 fitted with (working) duel air-con I intend to move across. However as stated I think using the existing bits but changing the way they are working is the go (ie: bypassing the existing heater box).

The aussie CX's have an evaportor/fan in the boot, blowing through the parcel shelfs (the hoses run under the car to the rear evaporator), and the air-con in the dash (which is completely overcome by heat saturation and in-adequate air-flow).

Lots to think about here. The air-con drive could be moved across however I then need to also move the a shaft driven hydraulic pump which will lower the output capacity of the pump (which causes you to lose steering when performing parking manuvours).

I've got a while to contemplate how I will go about this yet. Next winter is probably when I'll start !

seeya,
Shane L.

[Greg C]

Hi Shane

even though I have suggested some radical things I would counsel caution. I have said before and drive a car to prove it, the air con in a CX can be made to work quite well. If as you state it does not leak much heater hot air into the car you are half way there. Install the standard system from the 2400, carefully, and you should have quite good air. If the engine is out and you are OK with the look I would lag the whole underbonnet air trunking with aluminium foil backed airconditioning insulation. The tackle another known but forgotten heat source, the exhaust system. Remember how warm the centre console gets. I have seen one car that had a heat shield running the whole length over the exhaust pipe under the car. You could incorporate shielding the refrigerant lines to the rear evaporator at the same time. If you stick to details like this you gain a few percent here and a few percent there. Pretty soon you have gained 10-15% which makes all the difference

Greg

[DoubleChevron]

Originally Posted by Greg C

Hi Shane

even though I have suggested some radical things I would counsel caution. I have said before and drive a car to prove it, the air con in a CX can be made to work quite well. If as you state it does not leak much heater hot air into the car you are half way there. Install the standard system from the 2400, carefully, and you should have quite good air. If the engine is out and you are OK with the look I would lag the whole underbonnet air trunking with aluminium foil backed airconditioning insulation. The tackle another known but forgotten heat source, the exhaust system. Remember how warm the centre console gets. I have seen one car that had a heat shield running the whole length over the exhaust pipe under the car. You could incorporate shielding the refrigerant lines to the rear evaporator at the same time. If you stick to details like this you gain a few percent here and a few percent there. Pretty soon you have gained 10-15% which makes all the difference

Greg

Hi Greg,

I still need to overcome the appalling fan in the car.... Plenty to think about over the next few months either way

thanks
Shane.

[Sturla]

Here is a person who replaced the fan motor with one from a BMW. In Norway the problem tends to be direct opposite of yours Shane, nice and warm heater but the fan is too tired to blow properly, and the ice on the windows... This allegedly helped increase airflow.

http://www.aussiefrogs.com/~upload/6434/1196156516.pdf

[JohnW]

Originally Posted by Greg C

Hi Shane

a thoughts

1. Recirculation - I am pretty sure all CXs got this, the motor driven flap under the expansion bottle. I would get that going and use it

2. Another evap outside the normal air trunking. Not a bad idea but I would still blow air through the normal heater box because in mid season you will need to add a bit of heat I think. Also if you are going to this sort of trouble you will make a hot water cutoff valve and have it so the hot water is shutoff when the temp lever is all the way back

3. Further to 3 I think of it as kind of supercharging the normal system. That is one thing wrong with the CX, the amount of air flow through the front system very poor compared to say a Xantia.

4. Where is this extra evap going to pick up air. I would strongly suggest cutting into the existing trunking upstream of the existing fan, through the extra evap, extra fan then back into the extisting system. That way you can recirculate everything on really hot days and get good airflow.

5. Other things to do would be pull the heater box down and fit new foam to the flaps and then adjust so you can completely close off the flow through the heater when you don't wan't it

6. Use a space saver spare to give yourself more room

7. A simpler approach might be to shoe horn a Xantia fan in place of the normal CX fan. Simpler and it should make a big improvement.

Greg

Sounds sensible, but you could just buy a Xantia. They are so cheap these days that you can just about have one for hot days and keep the CX for cool/cold days. Come to think of it, hasn't Shane a Xantia too?

[George 1/8th]

Hi Shane, and fellow Froggies...

Shane, I thought we had all this sorted out, and that your CX had a much better heaterbox / aircon set up than mine.
I have the standard CX 2400 C-matic series one type...without the rear parcel shelf unit.
I tried the following...I replaced the original very weak fan with one from a Celica. One of the main reasons for giving the celica fan a try was because it was easy to access on a car I visited at the wreckers, and it was only about $12.00.
When I tested it out of the car, wiring it up across the battery it nearly took off, it really blew hard. I fitted it to the system...bugger all difference...a slight improvement only.
It almost needs a special voltage booster coil set up to get it to blow better.

I really think the BEST way to get an effective air con to work inthe CX would be to remove the glovebox completely and fit one of those bloody after market /under dash units. It's only 2 rubber hoses to go through the firewall, to the compressor etc.
Years ago I used to fit these things as a daytime job, and they do work well because they REMOVE the heat from the cabin and blow cold air right at you.
The only trouble is that they are noisy on full blast. BUT THEY WORK!
Shane, I don't like the idea of fitting the evap where the sparewheel goes because that does two things incorrectly...it stops you getting the heat out of the cabin...and you lose space for a wheel.
Air con does not just blow cold air at you...it removes the heat out of the cabin as well. It can't do that if it's under the bonnet, it will just cool down the under bonnet area...and not very well I reckon.
You might even be able to fit it right under to the point that you can keep the glovebox...but maybe not.
Good luck....
Cheers....George 1/8th

[DoubleChevron]

Originally Posted by George 1/8th

Hi Shane, and fellow Froggies...

Shane, I thought we had all this sorted out, and that your CX had a much better heaterbox / aircon set up than mine.
I have the standard CX 2400 C-matic series one type...without the rear parcel shelf unit.
I tried the following...I replaced the original very weak fan with one from a Celica. One of the main reasons for giving the celica fan a try was because it was easy to access on a car I visited at the wreckers, and it was only about $12.00.
When I tested it out of the car, wiring it up across the battery it nearly took off, it really blew hard. I fitted it to the system...bugger all difference...a slight improvement only.
It almost needs a special voltage booster coil set up to get it to blow better.

I really think the BEST way to get an effective air con to work inthe CX would be to remove the glovebox completely and fit one of those bloody after market /under dash units. It's only 2 rubber hoses to go through the firewall, to the compressor etc.
Years ago I used to fit these things as a daytime job, and they do work well because they REMOVE the heat from the cabin and blow cold air right at you.
The only trouble is that they are noisy on full blast. BUT THEY WORK!
Shane, I don't like the idea of fitting the evap where the sparewheel goes because that does two things incorrectly...it stops you getting the heat out of the cabin...and you lose space for a wheel.
Air con does not just blow cold air at you...it removes the heat out of the cabin as well. It can't do that if it's under the bonnet, it will just cool down the under bonnet area...and not very well I reckon.
You might even be able to fit it right under to the point that you can keep the glovebox...but maybe not.
Good luck....
Cheers....George 1/8th

Hi George,

hmm, must be in the cabin. The main problem I was thinking is the heating of the evaporator box as it's under the bonnet. The evaporator actually "cooling" the cabin as it's in there would be about as effective as sitting a big block of ice on the floor of the car. It must have huge air-flow through it (the airflow it what cools the car). I would be sucking the hot air from the car, and blowing the cold air back in (ie: recirculating the air, so your cooling the already cooled air from the car)...

seeya,
Shane L.

[DoubleChevron]

Chris stewart doesn't post here ... However here's what he thinks ...

Guess you have the Bryson CX2400 extra heavy duty twin evaporators?, If so
this is the way to go, the std Citroen thing is too small. Also guess you
have the Bryson Australian Mark 4 unit in the rear of your 2400, this is the
way they did them in the early 80's with a control almost identical to the
original GE wiring diagram. On my 2400 this system worked very well, on old
gas! The Sanko/Sanyo SD508 compressor is according to my advice, well able
to meet & exceed the service, even on new gas.

The standard CX25 old gas system even with a European Clima rear unit is not
worth a crumpet in our climate IMHO. But the CX25 runs leaner & hotter than
the CX24 = floor temps inside around the front of the exhaust tunnel of 55C
after only 15 mins on 70kmph running, it would be far higher than this when
really working.

So the first major problem is heat flow into the cabin from the exhaust.
Even in CX2400's when its in the 40C plus area the system just cannot cope
due this. But your turbo like a diesel would be cooler here.

The second & probably most critical part is airflow through the fan - at
maximum speed the fan is very near its choke point - in other words this is
the absolute maximum airflow you can get. You can test by putting a leaf
blower onto the bonnet vent - you won't get any more air inside.

So you need to revise the whole fan system - how, I've wondered & wondered,
its no good up rating the fan like Knut Stiennes in Norway did, it does no
good - the airflow is max. Behr did a brilliant max out design here, but
should have given more air - modern cars at full fan will almost blow you
out the door - the CX = modern systems on lo lo!!!

A friend thought he had solved the problem by installing an under dash front
unit, & removing the front muffler & console inside - it worked ok. up to
about 35C (full sun), but from then on was hopeless, virtually failing to
give any cooling at 42C.

IMHO to avoid you having a mental breakdown, save your CX for winter car &
get something that meets our conditions, most new Euros have caught up with
the Jap & Yank/Aussie cars now maybe even Citroen!

Now why did I buy a modern new car, its runs 24C inside on a 42C full sun
day & the coolant remains at normal:-)

CU
Chris

Hmm... I have two CX's here with duel air, I wonder which is which(they have different rear evaporators.

The one I was going to use sucks through one vent, and blows through the other three

seeya,
Shane L.

[Greg C]

Hi Again Shane

Rear units - the one that sucks from one and blows out the other 3 is the Autoclima unit fitted to 2500s in Oz. The other is the Windsor unit fitted to 2400s in Oz. If I had a choice I would use the latter.

However thinking further there are plenty of aftermarket units designed to fit under rear parcel shelves. Go to an Airconditioning specialist and look up his catalogue. I was almost going to go this way when I first put a rear unit in the Prestige, Bill Penfold even had a unit from a Toyota bus that would have fitted in the boot that he suggested but I had a Windsor unit already.

This could be the best way to go. Forget the front fan problem, it is always going to be a problem but you can make the most of it by maximising the performance of the front airconditioning, correct TX valve for the gas you use (I would suggest R134a) sealing etc. The factory rear unit we have blows a nice breeze over the front occupants heads when on full and that in a Prestige. A big rear unit will be less trouble and as the evaporator is not in the engine bay it will work better

Greg

[DoubleChevron]

Hi Greg,

seriouly the air could come out the front vents at -20degrees and have no effect... I'll try hot wiring the fan motor stragiht to the battery and see if that livens it up a bit (it's a transistor controlled fan.... I don't have high hopes for it but I'll check what voltage I have at the fan). Possibly leave all intact for "normal" functioning. However put a button inside the car that's hooked up to a relay. The relays N/C contacts allowing power through from the electonic control, and N/O is wired straight to the battery.

No rush, I've gots lots of other stuff to do. I think I'll order in some new engine mounts and possibly a 1/2nd and 3/4th synchro ... "while i'm there' (the synchros' work ok, but are slightly crunchy on cold mornings).

Anyone got a prestige hydraulic clutch for me to fit they want to sell

seeya,
Shane L.

[robmac]

Originally Posted by Greg C

Hi Again Shane

Rear units - the one that sucks from one and blows out the other 3 is the Autoclima unit fitted to 2500s in Oz. The other is the Windsor unit fitted to 2400s in Oz. If I had a choice I would use the latter.

However thinking further there are plenty of aftermarket units designed to fit under rear parcel shelves. Go to an Airconditioning specialist and look up his catalogue. I was almost going to go this way when I first put a rear unit in the Prestige, Bill Penfold even had a unit from a Toyota bus that would have fitted in the boot that he suggested but I had a Windsor unit already.

This could be the best way to go. Forget the front fan problem, it is always going to be a problem but you can make the most of it by maximising the performance of the front airconditioning, correct TX valve for the gas you use (I would suggest R134a) sealing etc. The factory rear unit we have blows a nice breeze over the front occupants heads when on full and that in a Prestige. A big rear unit will be less trouble and as the evaporator is not in the engine bay it will work better

Greg

The rear parcel shelf is an option. Have a look at the link below


http://www.jayair.com.au/PartDetails.aspx?PartID=1879

You would need to put in a box in the boot and duct the supply and return air into the cabin.

Jayair may have a purpose built evaporator (XJ6 Jags used in the boot/rear parcel shelf after market systems)

Not a cheap option.

As you would well know I strenuously oppose R134A as a replacement refrigerant.

Hychill HFC refrigerants are far better performers and a drop replacement for R12 systems in nearly all cases.

If the system was designed for R134A in the first place then it is OK I guess.

Parcel shelf systems tend to chill the the back of your head and neck.

Having said that it may be the easy way out.

If you can talk to Bill Penfold about it, that would be a good thing. He is an old timer and real expert in mobile aircon.

[DoubleChevron]

Well I'm bloody stunned, Gregs convinced me to do a little investigation ...

This is the airflow in my car ... (I've never tried youtube before, so lets hope this works ...). BTW: My wife thinks I"m even nuttier than usual after stealing a coat hanger from the cupboard and tearing a a tissue and sticking to it

Note: at the start of this film, the heater is on "FULL HOT", then I move the climate control to FULL COLD.



http://www.youtube.com/watch?v=ihyTeqk4lRg

Hmm... Like I said bloody hopeless ... Lets look a little further.

This is about where I can feel air when the heater is on



I turned the climate control to full cold ... to find this



Yes that's the bloody fan ... There is no restriction between the fan and vents in the series II cars .... WTF ???





What the hell... There's no inlet or outlet restrictions .... This bloody thing should blast me out of the bloody seat ?? The fact the fan is so weak is ludicrous. This definatly requires more investigation ...



Hmm... Well that seriously sucks ....

Hard wiring should show a little difference ....



I thought the alternator generally put out 13.2volts in this car ?



Damn ... There leads I've made up myself ... With soldered connectors and the power hungry fan is dropping the voltage hard wire to the battery by that amount

Here's the Xantias airflow to give a comparison...

http://www.youtube.com/watch?v=5hn4KgcLQ7E

Now here's the CX's airflow as a comparison ...

http://www.youtube.com/watch?v=bw_iJg4juoM

Nearly as good as the Xantia (mind you the Xantia is very average for a modern car). The difference being I have every other vent turned off in the Xantia, where as the CX is still blowing to the windscreen !

You know I think if I just put the evaporator in, but not the recirculation that will mess with airflow this may work !

seeya,
Shane L.

[chris]

If the car is reasonably well sealed, recirc might not be too bad for the airflow: it'll just let the fan push air around in a circle, rather than trying to force fresh air into an already-full cabin... I know the airflow through the vents on my GS goes nuts if I crack a rear window.

Chris

[Richard-C/Hbr.]

Hi Shane,
From reading all the posts on this subject, & your recent test results confirm, that at least part of the air flow problem may be due to voltage drop at the fan. Since the speed control resistors would be by passed in the maximum speed setting, why not fit just a relay & really heavy lead [ fused ] in the supply line to the speed controller, & a heavy earth lead direct off the fan. This would avoid having to fit a separate switch & should work just as well, & be more convenient too.
One other thought occurs. I don't know whether the CX has through flow venting, but I know that with some other imports the distributors used to block these off to prevent dust entry. Obviously this isn't important when using the recirculate setting, but it is not good for oxygen levels in the car to run permanently on that setting, so you do need some fresh air entry. Easy enough to test once you have achieved full voltage to the fan, by opening & closing a window & comparing flows.
Just thoughts Shane, which I hope might help, not trying to teach you to suck eggs.

Keep having cool fun !!
Richard

[DoubleChevron]

Yeah,

I'll most likely do what I suggested above with a relay straight from the battery....

just had a thought ... Something I will need to check, I have the top off the fan to get to it's power wires... I wonder if the restriction is a tiny gap above the fans for the intake air when the top is on.... I'll leave it hard wired to the batttery and compare top on fan, to top removed. Everywhere else has no restriction from what I can see. The fan should blow a bloody gale of air through ... If that's another issue, it's an easy'ish fix Two holes, and a nice bit of big pipe connecting the fan to the intake trumpet


seeya,
Shane L.

[Greg C]

Hi Shane

don't blame the wiring totally. You drop 1.4 volts accross the power transistor (0.7 across each junction). The solution as has been said a few posts back is to fit a relay that shorts out the transistor when you put the fans to full (just like on a BX although I am surprised it is not done on S2 CXs if they have the same transistor speed control). I would run a heavy earth cable from the motor back to the battery to eliminate the drop on that side and of course the relay will be fed straight from the battery with heavy cable. We are on our way to improving the front system so it will do its bit in concert with the bigger system sitting in the boot.

Note you should be able to see the fan from the main centre console outlet on the Behr heater. The reason you haven't seen it before is there is an evaporator in the way


Greg