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Thread: CX Heater Box

  1. #1
    Fellow Frogger! laurie_lewis's Avatar
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    Default CX Heater Box

    Well I am about to put my heater box back into my Series II CX.

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    What are the recommendations on what I should check before it gets bolted back in?

    Laurie

  2. #2
    Fellow Frogger! Rob T's Avatar
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    Very early cars had a horizontal axis motor and a water tap style heater. Later cars have a BEHR system with the fan motor vertical. Assuming you have the BEHR unit.....

    The heater has permanent water flow (it is always hot) and there is a pair of flaps that direct air over the heater. The flaps were originally covered with a foam rubber so that they made a positive seal when closed. The foam will have disintegrated over the years. I used some self adhesive polyurethane sheet foam about 3 mm thick to make up replacements. It is available in about 300 mm squares at Clark Rubber. Also make sure that the heater and A/C core both seal well on the sides so that all air is forced to flow thru the cores. I used stick on foam tape when assembling.

    When you install the unit in the car make sure that the A/C drain runs thru the hole in the floor. My car had a rubber boot that had seen better days. I used a short bit of tube and sealed around with more of that 3 mm sheet.

    That's all I can remember....
    Robert Thorne
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    Citroenless - for now...

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    Foam sealing strips will have rotted and make a difference.
    Check the fan resistance unit is not rusted if it has one mounted inside the case.
    Check the heater matrix end tanks are not aged and cracked, which you should really expect now. Now is the time to address that problem and replacing the matrix would be smart anyway. I've been on the receiving end of a burst heater core and it's not amusing. Very dangerous actually.

  4. #4
    1000+ Posts Greg C's Avatar
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    Replace the heater matrix. Even if it looks OK I'll lay money on it leaking as soon as the car is back together and all retrimmed. Don't ask me how I know this. Good advise to seal the heater flaps. When they are good very little heat leaks into the cabin from the heater core. On most CXs they are stuffed. I would do round the firewall and make sure everything is sealed up. You can even go the Double Chevron route and insulate everything, not a bad idea
    Mine

    CX Prestige
    Toyota Prius

    In the family

    Xantia SX

  5. #5
    Fellow Frogger! laurie_lewis's Avatar
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    Thank you,

    I was also thinking the A/C Unit should be tested as well.

    Greg, I have read Shane's thread again today and looked at his pics. I was just thinking that the insulation might be better on the inside, but I am concerned that this might impact on airflow. Guess I will have to look when I pull it apart.

    Heater matrix - local purchase or CX-Basis

    Laurie

  6. #6
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    I would be surprised if any locals would have a CX heater matrix on the shelf, but you could always ask!

    There was an imported Prestige that came in from Asia some years ago and was apparently modified in this area. Not really needing a heater there, but with A/C being rather useful, the heater matrix had apparently been removed and replaced with a much larger evaporator. I am told it had very effective A/C, which you don't get with the puny standard evaporator, especially if you further hamper it with R134a performance. Worth thinking about, depending on when you expect to use the car most.

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    Fellow Frogger! Rob T's Avatar
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    David, Laurie lives in Armidale so I think he will actually need a heater. There are days in a Brisbane winter when i use mine.

    My 1981 car had the plastic / aluminium heater matrix. It was leaking and disconnected when I got the car about 12 years ago. The plastic gets old and brittle and cracks. So definitely a good idea to replace it while it is in pieces.

    I had a new brass matrix made up by a local radiator shop who found a core the right size and made up tanks to suit. Cost about $300. Then I discovered that you can actually buy replacements at very reasonable cost. They are small and light so shipping from Europe shouldn't be too expensive. They do show up on eBay occasionally but I suspect that a lot of parts advertised are 'drop ship' i.e. they try to get the part if you place an order. It might be better to order directly from a supplier like GSF or CX Basis.

    I have added a manual ball valve to the hot water supply line. I turn it off during summer. It does make a small but noticeable difference to the ventilation air temperature. I haven't had any issues with the cooling system, although I do make sure the valve is open when changing coolant and bleeding the system.
    Robert Thorne
    Brisbane
    Citroenless - for now...

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    There's obviously a lot of drop shipping with eBay vendors and probably also with some bricks and mortar type outfits too, but I'd agree CX-basis is possibly worth a try for a heater matrix. Armidale probably needs a working heater, but it would be tempting to enlarge the A/C evaporator in a car that's not used in cold conditions.

    I fitted a generic vacuum tap in the heater line and operated it via a vacuum solenoid and a microswitch on the temperature lever. It did help a bit, but the A/C system is inherently undersized for our climate ans struggles.

  9. #9
    Real cars have hydraulics DoubleChevron's Avatar
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    Yep, I insulated it inside and out. You will see how it all works when you pull the box apart, so it will make sense where and how to seal it all up as soon as you see it. I covered the heater tract inside with insulation from memory too, as you always have that heater core sitting there like a big heating element radiatiating at least 90degrees heat, even without air flow through it.

    my A/C is quite usable, even without the heater core bypassed. It really does need an athermic windscreen though. Since we have got the 407 i have found it suffers the same "heat soak through windscreen" issue too. It's an incredibly hot car to leave parked somewhere, even on a cold day. The eletronic crap inside the car closes the sunroof no matter what you do .... as soon as you turn the car off, so you can't leave it cracked open to allow the heat out

    seeya,
    Shane L.
    'Cit' homepage:
    Citroen Workshop
    Proper cars--
    '85 Series II CX2500 GTi Turbo I
    '63 ID19 http://www.aussiefrogs.com/forum/citro%EBn-forum/90325-best-project-car-you-have-ever-seen.html
    '72 DS21 ie 5spd pallas (last looked at ... about 15years ago)
    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

    Yay ... No Slugomatics


    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual

  10. #10
    1000+ Posts Greg C's Avatar
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    CX basis has a heater matrix for 81 euro, add the 40 euro postage so you should land it for $A200 easily. Would be better if you bundled some other purchases too to share the postage of course. How are your gutter moulds?.

    http://cx-basis.de/eshop/product_inf...oducts_id=4790

    Speaking of athermic windscreens I need a new one so if anyone finds one I'll put my hand up. I'll look as well of course
    Mine

    CX Prestige
    Toyota Prius

    In the family

    Xantia SX

  11. #11
    Fellow Frogger! laurie_lewis's Avatar
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    Hi all,

    Well I pulled it apart today and found a few interesting things.

    The heater matrix actually looks VERY NEW. There was little evidence of leaking water in the heater compartment compared to the AC area.

    The evaporator I am not so sure about. The AC area was full of leaf litter. I saw that there was the original thermostat still inserted into the evaporator but another unit had been shoved into the side of the unit. It had been wired in off one of the large red wires that went to or came from the AC Electronic Control Unit (ECU). So I am now not sure if the AC ECU is working correctly and I have no idea on how to test it.

    Rubber all gone as you would expect.

    No hose to take away the water from the AC area

    The white plastic cog thing (technical term) that moves the arm controlling the internal flap was broken. I have glued it up and hoping it will be ok. I will have to test it obviously once it has dried totally. Using a two part glue called Rapidfix.

    So my questions for you knowledgeable people.

    1. How do I test the AC ECU to see if it is ok?
    1a. Does anyone know where you can get a replacement from (web search showed nothing)?
    2. How do I test the thermostat that was fitted (factory one) to see it is ok?
    3. Will take the evaporator to an AC place tomorrow for testing to see if it is ok - correct?
    4. Will get the heater matrix pressure tested to see if it is ok - correct?

    Greg, Yes I found that Heater Matrix on CX-Basis but could not find an AC ECU unit. If the Heater Matrix had looked like the evaporator I would not even be thinking of retaining the current one - it just looks so good.

    Shane, I can see one photo on your website that shows the heater box. Do you have any others - I can remember you also did some other modifications taking the wings off etc.

    I am sure there will be other questions. Any yes RobT you are 100% correct. Armidale needs a heater much more than an AC but I want to leave town sometimes so the AC is necessary also.

    RobMac - I am still working on how to integrate it with the rear just got sidetracked for a couple of months so if you happen to see this and remember our last conversations and there is something you think I should know I would appreciate your assistance.

    Laurie
    Attached Thumbnails Attached Thumbnails CX Heater Box-img_0024.jpg   CX Heater Box-img_0026.jpg   CX Heater Box-img_0027.jpg   CX Heater Box-img_0028.jpg  

  12. #12
    Fellow Frogger! laurie_lewis's Avatar
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    Well the Evaporator is stuffed.

    If anyone knows a local source could you please let me know. About to go off and look at CX-Basis.

    Laurie

  13. #13
    Real cars have hydraulics DoubleChevron's Avatar
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    There **HAS** to be a drain ... no wonder it's rotted out ... there must be plenty of moisture damage around the heater box.... maybe it leaks back through the fan housing under the bonnet if the drain is blocked, rather than inside the car?

    I'll see if I have an evaporater here. From memory the heater box is out of a couple of the cars.

    seeya,
    Shane L.
    'Cit' homepage:
    Citroen Workshop
    Proper cars--
    '85 Series II CX2500 GTi Turbo I
    '63 ID19 http://www.aussiefrogs.com/forum/showthread.php?t=90325
    '72 DS21 ie 5spd pallas (last looked at ... about 15years ago)
    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

    Yay ... No Slugomatics


    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual

  14. #14
    Fellow Frogger! laurie_lewis's Avatar
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    Thanks Shane,

    I have been told that the Evaporator out of a Peugeot 405 Series 1 that can be delivered to Australia for less than $200 - new. I am not expecting it to be any more efficient than an older one.

    Just speaking with Martin Bray and he thinks he has some good ones from 2500 models put away. I am no expert but the heater box looks the same as the series 1 models. Do you know if there are any differences.

    There was no drain hose and the bottom was full of leaf litter blocking everything. All the sides of the evaporator have rotted away.

    Laurie

  15. #15
    1000+ Posts robmac's Avatar
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    http://speedyairspares.com.au/produc...s-175-215.html Toyota

    http://speedyairspares.com.au/catalo...UNITS-2-1.html General

    Have a look at the links. The Tarago was nearly the standard add-in unit for modifiers for a few years. YR Taragos are easy to find in wreckers - get the complete assembly including the Tx valve. Look behind the drivers seat in the back right next to the door pillar . There is an access hatch in the floor - it's under there.

    Use some polystyrene (there are usually lots of scraps around building sites building "foam" covered house) type foam to fill up around the new evap coil. Adding an intake filter is highly recommended. Hardies colourbond sheet adhesive in the cartridge (grey urethane) will stick to anything and won't melt the foam. Cleans up with turps.

    Don't use supermarket foam container or fruit box foam. It's not stable in sun or long term and will crumble.

    Try to make the TX valve serviceable from outside. You need to enclose the whole tx and bulb tip/ line in presstite tape (black cork bitumen self amalgamating tape used for thermal insulation in a/c stuff)

    If you need to bend line be VERY careful. It's easy to break off where the line meets the modine coil.

    EDIT: The evap doesn't look that bad if you remove it, clean up and leak test it may be OK. Saturate with Nifti kitchen spray, soak for 15 mins, keeping it very wet with more nifti, hose off with the garden hose and dry with low pressure compressed air. Repeat a few times.

    A bit "finning" and it may come up like new.

    A few warnings. Remove from the case and remove the thermistor, electronics and all insulation.
    Don't use a pressure washer or high pressure air -these bend the fins. I know

    Plug the ends of the refrig line with proper caps or plug with gloop of silicon and screw (to pull out the silicon later).
    Last edited by robmac; 17th December 2012 at 12:19 PM.

  16. #16
    Real cars have hydraulics DoubleChevron's Avatar
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    I dont' have any readily accessable evaporators here I just checked. Two cars have the heater box in bits, but it's only the underbonnet part removed. The cars are still intact inside. There's no way I'll have time to pull the dash and center console from a car in the near future

    Martin Brays 2nd hand prices are often multiples of what you can buy the part new from ebay out of UK, so you need to be careful Your welcome to have one from a car here if someone can pull it out.

    seeya,
    Shane L.
    'Cit' homepage:
    Citroen Workshop
    Proper cars--
    '85 Series II CX2500 GTi Turbo I
    '63 ID19 http://www.aussiefrogs.com/forum/showthread.php?t=90325
    '72 DS21 ie 5spd pallas (last looked at ... about 15years ago)
    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

    Yay ... No Slugomatics


    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual

  17. #17
    Fellow Frogger! laurie_lewis's Avatar
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    Thanks Shane,

    Problem is I can't find any overseas at this time. Unfortunately no way for me to get anyone out there. Currently seeking some other alternatives. Waiting for some info from UK as to 405 unit.

    I also have to find a replacement white plastic unit as gluing did not work. Didn't expect it to actually. Photo of piece I am talking about attached. On drivers side and works main flap.

    Laurie
    Attached Thumbnails Attached Thumbnails CX Heater Box-image.jpg   CX Heater Box-image.jpg  

  18. #18
    Real cars have hydraulics DoubleChevron's Avatar
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    Quote Originally Posted by laurie_lewis View Post
    Thanks Shane,

    Problem is I can't find any overseas at this time. Unfortunately no way for me to get anyone out there. Currently seeking some other alternatives. Waiting for some info from UK as to 405 unit.

    I also have to find a replacement white plastic unit as gluing did not work. Didn't expect it to actually. Photo of piece I am talking about attached. On drivers side and works main flap.

    Laurie
    Oh gee's, I can't promise to send you one even in the near future, I'll see if I can get an evaporator out of one of the cars over the xmas break (i have a week or so off work). That cog is usually stripped. The way it works is the little drive motor is constantly powered by design, so it drives to either end of the gear and sits stalled indefinatly until the flap is moved, then it drives to the other end of it's track ... and once again sits stalled indefinately. You shoudl find another workng on the same principle on the recirculation flap under the bonnet.

    I'll see if I have an unbroken gear here. It's probably been broken from someone kicking it frustration to stop the "clicking". I find tensioning the motor against it slightly has stopped the teeth jumping in my car. I'll need to verify it's the same as the recirculation flap, otherwise I don't have a spare. Only the later cars without the cable/lever adjustments had the engine driven flap inside the car.

    seeya,
    Shane L.
    'Cit' homepage:
    Citroen Workshop
    Proper cars--
    '85 Series II CX2500 GTi Turbo I
    '63 ID19 http://www.aussiefrogs.com/forum/showthread.php?t=90325
    '72 DS21 ie 5spd pallas (last looked at ... about 15years ago)
    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

    Yay ... No Slugomatics


    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual

  19. #19
    1000+ Posts Greg C's Avatar
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    Hi Laurie

    I have a spare evaporator from a 1978 CX. I can't vouch for its condition but I think it should be OK. It is from a Behr heater box so should be OK for your machine. send me a PM
    Mine

    CX Prestige
    Toyota Prius

    In the family

    Xantia SX

  20. #20
    Fellow Frogger! Rob T's Avatar
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    I also have a used but serviceable evaporator. And I think Ive got one of the quadrant gears too but will have to find it.
    Robert Thorne
    Brisbane
    Citroenless - for now...

  21. #21
    Fellow Frogger! laurie_lewis's Avatar
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    Thanks for the offers. I have found and purchased the parts needed at this time.

    I do have a couple more questions but will wait till I have a big keyboard to type on.

    Laurie

  22. #22
    Fellow Frogger! laurie_lewis's Avatar
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    Hi all,

    If you get a chance to watch "Skyfall" I can recommend it. You may have a sore bum though as it is a long movie.

    Back to the topic .....

    I have been looking at the wiring, the owners workshop manual and the owners manual - specifically for the turbo. It is very different from my CX2400

    The Workshop manual indicates that there are 2 temperature sensors linked to the AC system in the car. One in the light console on the roof and another inthe passenger footwell (I have to find this one as yet). If you look at the attached picture you see that the centre console fitting has a fan speed control on the left that is a resistor based device. The temperature control on the right shows temperatures so from this I have made an assumption that it is temperature controlled as in modern cars.

    Below the vents you have a number of switches. From left to right.

    Ventilation Switch: Turns ventilation onto screen and side vents only (on) or full vents (off)
    Recirculation Switch: Fresh air in (off) External vent open - recirculate air from inside car (on) External vent closed

    Next switches are for the AC

    2 Snow Flakes:- AC on external vent closed and air recirculated in car (internal air re-cooled)
    1 Snow Flake:- AC on external vent open and air from outside cooled

    So, I wan to make this work as originally fitted. That is remove the after market thermostat and revert back to original thermostat setup. I am thinking this would be how it was designed to work. The question is how do I test whether it is working properly?

    Second is back to an old thread on the newly fitted rear AC unit. What I want in the setup is:-
    1. Able to turn if on/off from the front when I do not want to use it (Power Switch)
    2. Have it linked into the front AC unit, using the temperature controls fitted. Now here I make an assumption that when the front AC gets to the set temperature it will turn itself on/off. What I want is when the front AC unit turns itself off the rear unit turns itself off.

    Now I am thinking that I can achieve this with a relay having it in line with the AC switches and from there to a power switch in the centre console and then power back to the rear AC unit. The rear AC unit will obviously need it's own thermostat so it does not freeze up etc. My thinking is that cutting power to the rear based on the front AC thermostat would make them work as one. Perhaps the switch could be a pod type so it could alter the fan speed in the back. Perhaps it could even be where the rear passengers could reach it.

    I have to go back over my previous emails with RobMac to check a few things but I hope that describes what I am trying to achieve.

    Any further advice?

    Laurie
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  23. #23
    1000+ Posts Greg C's Avatar
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    You will have to have a thermostat for the rear unit that controls a solenoid valve that shuts of refrigerant flow to the rear unit. If you rely on the front unit controlling the temp for both units the rear passengers will freeze as there is less heat load in the rear and the rear evaporator is bigger than the front. I have yet to do this to mine but if you want really good aircon it must be done. Robmac is covering this topic over in the DS aircon thread. Apparently Taragos that had rear air have just the bits we need. I have a thought of having an air temp thermostat in the rear compartment but I don't know wether they are readily available. A thermostat on the coils of the rear unit would also be a good idea to control icing up of the rear unit that impedes efficiency. With an air temp thermostat you could have the control on the centre console with the fan speed control so they can be controlled by the driver.
    Mine

    CX Prestige
    Toyota Prius

    In the family

    Xantia SX

  24. #24
    Fellow Frogger! Rob T's Avatar
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    Laurie, I promised a long time ago to draw a diagram of the circuit in my car. Will do it in the next few days.

    As Greg says, the heat load in the back is much less and the rear unit needs its own themostat. That also implies that it needs a solenoid to cut of refrigerant gas flow. The rear fan must be wired so that it runs on low speed any time the system is switched on - otherwise you will get rapid icing up in the rear evaporator.

    My car has a really basic system with a thermostat that is only accessible form the boot (because I already had a short one and fitting it into the rear box unit is simple) and refrigerant solenoid all squeezed into the rear box. There were photos in old thread but I couldn't find it when I was searching recently. It must have been a victim of the crash. The rear system isn't capable of switching the compressor on and off. It works on the assumption that it demands much less refrigerant than the front and that the refrigerant will always be available becuase the front system is always on in anything but very mild weather. In sounds a bit crude but it works fine in practice. There is a three speed fan swith in the raer of the centre console that rear seat passengers can reach. Once you get the rear thermostat setting right (a bit of trial and error) rear temp can be controlled by turning the fan up or down. Not as good as modern car - but it IS an old Citroen... what would you expect.

    Don't try to get too sophisticated. This simple system works OK.
    Robert Thorne
    Brisbane
    Citroenless - for now...

  25. #25
    Fellow Frogger! laurie_lewis's Avatar
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    I still do not understand electrical diagrams.

    I have a diagram from RobMac with a solenoid included so it works independently with just an on/off switch. I have a better understanding now if how the front system appears to be wired. What I want is that the rear AC unit will not even work if the front AC is off. I think I would be using a relay from the AC switches in the front so that if AC off power would be cut to the rear unit.

    The plan would be 12 V from battery ---- inline fuse 20A ---- relay ---- on/off switch centre console ---- rear AC unit. Relay wired to AC switches in front so if either turned on connection made. If neither AC on then relay open - no power to rear.

    From RobMac's diagram I understand that I need 2 lots of 12V for the rear AC. One lot goes to the thermostat which in turn controls the TX valve etc. The second goes to the fan/blower. So best case scenario for me would be a switch that has 12 V in and 2 lots of power out. 1 X 12V constant when on and the other say a 3 speed switch to vary the blower speed. So two power wires from boot back to centre console for the AC. Earth in boot.

    Hope that makes sense. If that is correct I can put the wires in place as I am refitting interior and finish up later.

    laurie
    Last edited by laurie_lewis; 17th December 2012 at 11:50 PM.

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