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Thread: Cleaning fins of the A/C evaporator coil

  1. #1
    Join Date
    May 2008
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    Camp Hill, Brisbane
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    191

    Cleaning fins of the A/C evaporator coil

    So, I have sorted my A/C with a replacement compressor and have an evaporator temperature down to 4 deg. C. The airflow out of the vents is not spectacular even on full fan speed and the air temperature is cool, but nowhere near the evaporator temperature even with the blend flap manually flipped to cool. Therefore, I think this must mean an externally clogged evaporator with dust, leaves etc...
    Tried some A/C cleaner through a micro irrigation jet but no joy. Can I hope to clean it in place? If I do have to remove the dash (again!), can the heater unit be split off it so I don't lose my refrigerant (again)?
    TIA
    Steve
    '95 HSE

  2. #2
    Join Date
    Jan 2016
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    Netherlands
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    213
    Steve, mate I'm sorry, but if memory serves it is pretty much impossible to get to there without taking it apart. The large black heater box needs to come out and taken apart. MAYBE you could do it in situ but I do recall there to be screws far enough away that you cannot reach them... A complete rermoval of the dash, the metal frame and both blower motors is needed though since they are all connected to the central HEVAC box. I have a ripped apart spare parter in the shed and I could make some pics for you if you like

    Cheers!

    -P

  3. #3
    TheTree is offline ChatterBox Silver Subscriber
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    Feb 2013
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    Gosford, NSW, Australia
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    Mate

    Prelude is correct as I found out in this thread !

    Air Con evaporator replacement

    I am still getting the energy together to do this job

    Steve
    MY96 4.6 HSE P38. Niagara Grey; "The Phoenix"
    MY99 4.6 HSE P38. LPG, Blenheim Sliver; "Voldemort" burnt to a cinder
    MY79 RR Classic, Gone, MY57 Series 1 SWB, Long gone
    P38 write ups and info on my website http://p38.hts.com.au/

  4. #4
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    https://www.aulro.com/afvb/images/attach/jpg.gif
    So, I get this far by removing the bar across the front of the unit and pulling off the front assembly with flaps and heater matrix. One screw needs to be removed to separate it. Still can't get to the inlet side, but the evaporator seems remarkably clean! Sprayed with cleaning fluid and ran it to icing-up point. Now have discovered left blower is not working. HEVAC is complaining that the blower motor is open circuit + another six gripes. Plan is to leave evaporator for now, and work on getting airflow maximised. Also have a plan to ditch the HEVAC entirely and put my own controller in...
    By the time I chase blend motors and blower relays etc.. I may as well DIY.
    Cheers,
    Steve
    Attached Images Attached Images

  5. #5
    Join Date
    Feb 2010
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    Silly thought/question, and Iím sure you tried this before even considering a dash-out job.

    Have you replaced the blower motor relay and tried again? A good opportunity to see if youíve got cracks in your fuseboard.

    Cheers
    Keithy

  6. #6
    Join Date
    Jan 2016
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    Nice job steve

    Keithy has a good point about the blower motor. Regarding putting in your own system: I have been contemplating exactly that for a year now. Also replacing the blend motors with something made out of metal or at the very least a bit more sturdy and powerful.

    What kind of solution are you contemplating? I have been thinking along the lines of an arduino. Not sure how I would make the human interface though. Also, I would need to replicate the logic of the original unit, ie. temp x with sun y makes the fan go speed z and the flaps are in positions 1,2,3 etc. I am pretty sure that it is not by forumula but a simply map or table that should be recreated. If I am ever going this route, I'll replace the BECM and ECU as well. an arduino with expansion boards can handle everything the BECM does right now but CAN be water proof (and more field repairable since it is open) and replacing the ECU with a megasquirt takes care of that. Last but not least the gearbox ecu can be replaced by a compushift

    Anyway! I digress and I would not want to hijack your topic

    Cheers!

    -P

  7. #7
    Join Date
    May 2008
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    Quote Originally Posted by Keithy P38 View Post
    Silly thought/question, and Iím sure you tried this before even considering a dash-out job.

    Have you replaced the blower motor relay and tried again? A good opportunity to see if youíve got cracks in your fuseboard.

    Cheers
    Keithy
    Hi Keithy,

    Yep, been there done that. Resoldered the fusebox and have good supply to both blowers. It's just missing the drive signal to the relay on the LH blower unit. I suspect if the HEVAC detects a short or open circuit and then takes that motor offline until the error is cleared.
    Prelude,
    Thinking Teensy Teensy USB Development Board (because I have some) and it has up to 12 PWM outputs for servos. This should allow me to put conventional hobby servos in place of the blend motors. Even three high torque metal geared servos are cheaper than one blend motor. Have ordered a couple of PWM controllers (12V, 20A) for the blowers. To keep it simple, I'll emulate a Holden Commodore - rotary switch for fan speed, ignore solar and ambient temperature input. Just drive the A/C request line to ECM and the compressor relay signal while checking evap. temperature to prevent icing-up. Could get fancy with some PID algorithm, but just blowing some cold air would be a significant milestone currently. The more I dissect this thing, the more I see it suffering from over-engineering. As everything in the system ages, the faults just compound each other.
    First tasks are to install servos on cable actuators to the heater box while it is on the carport floor and make up a panel to replace the HEVAC.
    Stay tuned...

    Cheers and thanks
    Steve

  8. #8
    Join Date
    Aug 2015
    Location
    Moe
    Posts
    277
    Quote Originally Posted by zzsteve View Post
    Hi Keithy,
    [delatia]
    The more I dissect this thing, the more I see it suffering from over-engineering.
    Steve
    What ? Land Rover over engineer something ? Heaven forbid that that would ever happen.
    Cheers,
    Mark F...
    Vk3KW / VK3ZMF

    2000 Disco 2 Td5 Manual - Current
    197? Range Rover -Petrol - gone
    1973 SWB SIII Diesel - gone
    1968 SWB IIA Petrol - gone
    195? SI - Petrol - gone
    Balance Trailers forward fold camper trailer.

  9. #9
    Join Date
    May 2008
    Location
    Camp Hill, Brisbane
    Posts
    191
    Quote Originally Posted by Markf View Post
    What ? Land Rover over engineer something ? Heaven forbid that that would ever happen.
    Stay calm,
    It's a Valeo device - French.
    S

  10. #10
    Join Date
    Oct 2011
    Location
    Fremantle WA
    Posts
    2,078
    Quote Originally Posted by zzsteve View Post
    Hi Keithy,

    Yep, been there done that. Resoldered the fusebox and have good supply to both blowers. It's just missing the drive signal to the relay on the LH blower unit. I suspect if the HEVAC detects a short or open circuit and then takes that motor offline until the error is cleared.
    Prelude,
    Thinking Teensy Teensy USB Development Board (because I have some) and it has up to 12 PWM outputs for servos. This should allow me to put conventional hobby servos in place of the blend motors. Even three high torque metal geared servos are cheaper than one blend motor. Have ordered a couple of PWM controllers (12V, 20A) for the blowers. To keep it simple, I'll emulate a Holden Commodore - rotary switch for fan speed, ignore solar and ambient temperature input. Just drive the A/C request line to ECM and the compressor relay signal while checking evap. temperature to prevent icing-up. Could get fancy with some PID algorithm, but just blowing some cold air would be a significant milestone currently. The more I dissect this thing, the more I see it suffering from over-engineering. As everything in the system ages, the faults just compound each other.
    First tasks are to install servos on cable actuators to the heater box while it is on the carport floor and make up a panel to replace the HEVAC.
    Stay tuned...

    Cheers and thanks
    Steve

    I see a growth industry developing here!!!! Might even pay for your retirement in due course.
    Dan - MY04 D2a TD5 auto Classic (2nd engine @ 153K) set up for touring
    Bessie - MY95 RRC LSE Vogue SoftDash with MY99 TD5 and 4HP24 transplant

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