Cleaning fins of the A/C evaporator coil

[zzsteve]

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

[prelude]

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

[TheTree]

Mate

Prelude is correct as I found out in this thread !

Air Con evaporator replacement (https://www.aulro.com/afvb/p38a-range-rover/258748-air-con-evaporator-replacement.html)

I am still getting the energy together to do this job

Steve

[zzsteve]

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

[Keithy P38]

Silly thought/question, and I’m 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 you’ve got cracks in your fuseboard.

Cheers
Keithy

[prelude]

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 :D

Anyway! I digress and I would not want to hijack your topic :oops2:

Cheers!

-P

[zzsteve]

Silly thought/question, and I’m 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 you’ve 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 (https://www.pjrc.com/teensy/) (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

[Markf]

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.[bigwhistle]

[zzsteve]

What ? Land Rover over engineer something ? Heaven forbid that that would ever happen.[bigwhistle]
Stay calm,
It's a Valeo device - French.
S

[gavinwibrow]

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 (https://www.pjrc.com/teensy/) (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.

[prelude]

Steve,

I can see where you are coming from :) the KISS method is always preferred but (hence the nickname) I come from the honda world and I have built in climate control in prelude's that were never fitted with them. Sure, I used JDM spec parts but I really do like that complexity. My main gripe with landrover (valeo) is the quality of the stuff combined with the complexity. Most honda's built in the UK from the 90's are as reliable as their japanese counterparts, except for the crap that is put in there to make europe happy. ie. valeo anti-theft stuff, wiper motors etc. GUESS what breaks down? exactly.

So I am looking to build a complete climate control system, initially controlled by simple buttons, that I can expand further on into say a touchscreen display like in the tesla model 3 and many more modern vehicle's. I would love to keep in touch regarding the metal stepper servo's. I can figure out quite easily how to make a bracket to mount them but I have yet to figure out how to deal with the plastic gear on the heaterbox. Should I replace it with a metal one (and how to go about that) or just leave it be for the time beeing.

Anyhow, keep us posted mate! I will gladly borrow some of your ideas [wink11]

Cheers!

-P

[zzsteve]

OK, the servos on push-pull cables won't work as the friction makes it a bit marginal with the standard servo torque. Looking at direct drive on two and a short bell crank on the other. I have some bracket/mount drawings ready for laser cutting. Will post as it goes. I also wanted to convert the temp sensors (evap, heater, and ambient) to 10K thermistors to make the interfacing easier.
BTW what is the 'plastic gear' on the heater box you refer to? It's all plastic from that I can see.
Cheers,
Steve

[prelude]

Hi Steve,

trying to keep my quota on the site in check so I am linking to external pictures, let's hope this works :)

I was referring to this specific cog: https://ixquick-proxy.com/do/spg/show_picture.pl?l=english&rais=1&oiu=http%3A%2F%2Fwww.rangerovers.net%2Frepairdetai ls%2Fblendmotor3.JPG&sp=eab17c1dbd3bad91244911248bca8b3f

that fit's into this contraption: https://ixquick-proxy.com/do/spg/show_picture.pl?l=english&rais=1&oiu=http%3A%2F%2Fwww.rangerovers.net%2Frepairdetai ls%2Fheaterrhflaps2.JPG&sp=b51b0ba29042b8fa11caa8348830f279

when the blend flaps start to run heavy with age, a lot of stress is put on these two parts no doubt and I am not sure I can make that out of metal personally :)

Cheers,

-P

[zzsteve]

Gotcha.
Yep, that splined thing is just way too exotic to contemplate copying. I think I can fix a servo wheel directly to the plastic surrounding the female part. The servo can then engage with it's own splines on the wheel. This may not work for all three so a short push rod is in order for one of them. You will see they all have a 5mm hole on a lever for a cable actuator which must have been used in some way, either on a LR or some other manufacturer Valeo conned into using this heater box!
Hopefully some pics of some components this week to make it clearer.
Cheers,
Steve

[Scouse]

Why don't you source the parts from a non-climate control P38?
The panel might not have the A/C switch fitted but I'm sure parts could be swapped over.

https://www.aulro.com/afvb/attachment.php?attachmentid=137774&d=1521507493
137774

[zzsteve]

Thanks Scott,
Yep, saw these, but would have had just as much effort sorting out drive to the blowers, recirculation motors and A/C request signals to the ECM.
BTW: Which models/years had these fitted?
Steve

[Scouse]

BTW: Which models/years had these fitted?As far as I know, all non-A/C P38s had this control panel. All cars sold here had A/C though so you'd need to get one from Europe somewhere.
There's only one fan switch so the blowers would be linked & controlled manually. I don't know if the blend motors were electronic or cable operated though.