CX series 1 alternator 100A information

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cx25gtit2

Member
Tadpole
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Dec 19, 2010
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Location
the netherlands
Hello, for my series 1 CX Prestige, I have from an export Prestige donor the rear AC setup, located behnd the rear seats, to be installed into mine.
From the documentation from Citroen, they used a stronger alternator, for 100A, to run the extra system/rear fan. Or even a double alternator setup.
This was for CX vehicles designated as Outre-Mer or Grande Export .
In my donor was a regular 70A alternator.
Since this rear setup was also in CXs down-under, I was wondering, is there anybody with a CX with this setup ? With what alternator set-up ? 70 A? 100A? or a double ? Is it even possible lo locate a 100A alternator old, or a modern version new ?

any info is appecriated !
 
most sold here had the 100amp setup. Its not very good at generating amperage at idle (where C-matics with A/C needed it hte most). Its not very reliable as it has much much wiring. There is a big external rectifier swinging in front of the radiator, and usually and aftermarket regulator (as the internal one dies on the alternator).

A much better fix is to fit a modern bosch univeral 100+amp alternator that is internally regulated and rectified.
 
That is a helpful comment.
My garage will start working on it next week. I Talked to them about this. They have extensive experience working on Citroen CX, DS, SM, also on upgrading a modern alternator. For the CX a 100A version specifically they haven't done this before. In europe there a hardly any CXs with this setup.
So we have to find what would work / fit in a CX (2400inj series 1). If anyone has a tip on what modern 100A would work, that would be great.
 
a bosch universal altnerator (fitted to most GM vehicles) is all you need. You modify/make brackets to fit it to a CX. they are cheap, available from nearly any wreckers, reliable and cheap to repair.
 
I talked about it with my CX garage. They looked at the setup, and think that since I already have a new/modern alternator (70or 75A) that that should work. I must be better then the old alternators. The rear AC system is almost mounted in my prestige. They / I will surely check it. If it seems not adequate, I can always have a larger capacity alternator installed.
 
Double Chevron is correct. You might also need to make up a special composite hose to avoid it rubbing on the modified tightening bracket. Why would Citroen fit 100 or 110 amp alternators if it wasn't needed? I fitted that universal Bosch alternator and it worked perfectly well for years.
New hose set up for installation.jpg
 
Right. I will discuss this with my CX garage. To install a complete AC system is quite some work, that is almost done. The alternator can still be changed after that.
 
cx25gtit2 said:
Right. I will discuss this with my CX garage. To install a complete AC system is quite some work, that is almost done. The alternator can still be changed after that.
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Yes, I surely admire fitting AC if it wasn't there. Mine had the rear system as well. One issue is the heat that penetrates from that transverse engine - Mr Double Chevron actually insulated the inside of his whole body shell, such a good idea. You might check whether the small air vents just behind the rear doors, under the aluminium panel, are clear. Mine had tape over them!!
 
Do you mean the openings in the metal of the C pilar ?

I woud assume these are and should be open.

In mine, the current/existing front AC system is replaced with new parts: hoses, dryer, AC pump, condensor. And then the addition of the rear ssytem. I have seen mr DC and his insulation - great !! That must help !! Now, a large portion of my interior is out/open.... I may see how for I will go..... We don't have the high temperature summer days as you have though.
 
cx25gtit2 said:
Do you mean the openings in the metal of the C pilar ?

I woud assume these are and should be open.

In mine, the current/existing front AC system is replaced with new parts: hoses, dryer, AC pump, condensor. And then the addition of the rear ssytem. I have seen mr DC and his insulation - great !! That must help !! Now, a large portion of my interior is out/open.... I may see how for I will go..... We don't have the high temperature summer days as you have though.
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Yes, those openings are the ones. I read once that some were closed with tape, so had a look and mine were like that! I do not understand but when I unscrewed the aluminium panel, the opening behind was blocked off with adhesive tape. Very strange.

I fitted a new compressor and modified the pulley system to have two belts not one, which takes a lot of strain off the water pump shaft extension. This is a 1980 CX Pallas C-matic.
 

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When i had a 1969 CX 2400 cmatic in the early ‘90s, I measured the current draw of the two radiator cooling fans, the front blower motor and the rear blower. It was around 40A from memory. 40A + at idle is why you need a 100A alternator. After restoring the 100A factory alternator with external diode pack (the diodes fail) and upgrading the wiring and still having issues, I bought a 100A bosch, had the body machined to mount in the original position and it was dramatically better. The other thing is the rear unit is actually going to do most of fhe cooling work. The front airflow is crap so making sure air can recirculate from inside the car (under the back seat) and not just be sucked from the boot. The electric front recirculation flap motors burn out as they stall rather than turn off. I think i have a circuit diagram somewhere for a timer circuit and relays to time this for open/close operated by a recirculate switch.
 
Just a generic comment on big alternators. All new cars have 'big' alternators these days and nothing comes with 40-60 A even three cyl cars. Actually it has been shown that a bigger alternator uses less power overall normally because it runs in a more efficient operating area of its operation. The other good part is the increase in output at idle. This is important because of the need to ensure the voltage does not drop off with the modern electronics.
Also gear up the drive to get the alternator speed high. Of course modern cars use multi rib drive belts too which work better.
Good luck jaahn
 
blahblah said:
When i had a 1969 CX 2400 cmatic in the early ‘90s, I measured the current draw of the two radiator cooling fans, the front blower motor and the rear blower. It was around 40A from memory. 40A + at idle is why you need a 100A alternator. After restoring the 100A factory alternator with external diode pack (the diodes fail) and upgrading the wiring and still having issues, I bought a 100A bosch, had the body machined to mount in the original position and it was dramatically better. The other thing is the rear unit is actually going to do most of fhe cooling work. The front airflow is crap so making sure air can recirculate from inside the car (under the back seat) and not just be sucked from the boot. The electric front recirculation flap motors burn out as they stall rather than turn off. I think i have a circuit diagram somewhere for a timer circuit and relays to time this for open/close operated by a recirculate switch.
Click to expand...
Good to see you are still out there!
 
Air intake is from the passenger compartiment which is then cooled and returned through the 4 parcel/hat shelf.
Citroen documents start that the rear seat is modified for air to be able to be sucked in, but doesn't describe how.

Does anybody know? Is the bottom seat part altered ? Of the back rest somehow ?
 
cx25gtit2 said:
the double AC belt looks nice !!

I will see what happens with my current alernator with amps
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It took a bit of maching of stock pulleys but I reckon dramatically reduced belt tensions. A single belt to a compressor is asking a lot.
 
cx25gtit2 said:
Air intake is from the passenger compartiment which is then cooled and returned through the 4 parcel/hat shelf.
Citroen documents start that the rear seat is modified for air to be able to be sucked in, but doesn't describe how.

Does anybody know? Is the bottom seat part altered ? Of the back rest somehow ?
Click to expand...
Sorry, I have no idea. There was more than one system of supplying the four vents behind the rear seat too. Mr blahblah might know as he did a lot to that CX (which I owned next and which is still going well here in Western Australia).
 
If I remember correctly the dual system aircon sold in OZ was a local ( Sydney ? ) design... so likely to not be like the one fitted to this Dutch CX. Heat transfer and sink was always a CX problem. At launch in Brisbane a wise Dutchman ( a well known CCCQ member ) actually measured the roof and declared "This thing has more front and rear glass than roof area"... and that was a big problem in tropical sunlight. The actual low volume of air admitted to the interior is well documented, even extra inlet scoops being available to go atop the bonnet. It was common practice here to completely shut off coolant flow through the heater matrix, for the hotter months. Mods with cable controlled water taps were documented on AF too.
 
JohnW said:
Sorry, I have no idea. There was more than one system of supplying the four vents behind the rear seat too. Mr blahblah might know as he did a lot to that CX (which I owned next and which is still going well here in Western Australia).
Click to expand...
Mine has 4 rear vents. 2 for cool air and 2 intake
 
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