Author Topic: ACC overhaul - Heater box / evaporator removal  (Read 25223 times)

ckamila

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #15 on: 03 February 2012, 09:40 PM »
I am in way over my head but things seem doable with forum help and service manuals.

Currently stuck removing evaporator core from box as the ETR switch wire is preventing further removal at this point. Time to locate a good a/c shop here in Seattle. Anyone know of any decent shops to test evaluate evap and heater cores? What is the proper procedure from here? I did not start out planing to go THIS FAR at all! Original problem was a shutdown issue linked to torn defrost poddiaphragm....LOL


Is the evaporator core OK? ???  There is a fair amount of rust at sides.





ETR wire - i have disconnected ETR switch and gently pulled but don't wish to damage core. How to remove???





« Last Edit: 04 February 2012, 07:13 AM by ckamila »
If it's not broke i haven't fix it yet...


1980 300SD, 170K
1985 300D, 235K

KenM

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #16 on: 06 February 2012, 04:26 AM »
Brave man Chris, your scope of works has certainly ballooned out on you there, no going back now. I continue to be amazed that you can still get R12 in the US, it must be starting to dry up though.

The issue with the barrier hoses is that 134a does indeed have a smaller molecular structure than 12, not as small as some other newer refrigerants and if your hoses are in good condition it is likely not

to be a problem, but if your hoses are 10, 15, 20 years old or more they are most likely porous to some extent anyway so replacement would not be a bad idea whichever refrigerant you choose. The

other thing to keep in mind is that O rings, the compressor shaft seal and other components may not be suitable for the synthetic oils that R134a requires. If you are replaceing the compressor make sure you

get one with seals suitable for 134a, you can still run R12 in it. That black goop around the tx valve is tar impregnated cork tape, clean it up with kero, very messy. You can buy a roll of new tape from a

supplier. I'm not familiar with the ETR switch you have there, but you will probably find that the end is just pushed into the coil, or there may be a small pocket that it slides into attached to a tube in the

evap.  Not much to be done about the rust on the evap end sheets, it shouldn't cause any problems by way of generating a leak, maybe hit it with some rust converter and paint over.

Good luck, you're going pretty well so far, keep us posted.

Cheers,     
Mexican girl: 'We could go for a walk outside and you can kiss me on the verandah'
Chevy Chase: 'On the lips will be fine'

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jbrasile

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #17 on: 06 February 2012, 04:29 AM »
Hi Chris,

Sorry I haven't been around much, just very busy right now!!!

Wow!!! You are doing what is probably the most complicated, time consuming and expensive jobs on a a 116 or any car for that matter!

1) R-12 vs R134 - if your system is leak free and you can get 12 in your area go for it, otherwise bite the bullet replace the drier, expansion valve and go 134. You are going to need a new compressor anyway so no need to overhaul the old one. As far as hoses, I did not replace mine and have had no leak issues for the past 18 months. Mi expansion valve was not changed either and I do notice  a slight drop in efficiency on super hot days but only up until the system is on for a little while, then all is normal

2) Your evap looks fine from the pictures, they are made out of copper and will last forever! To clean the evap, heater core and heater box you should use soap and water with the help of a brush, to work the tight spots, fins, etc...

3) ETR switch - as far as I know the capillary tube is simply inserted into the evap core through a tube, spray some wd 40 and see if it starts to pull out

4) Grommets:

107 997 01 81 - heater pipes through firewall - $12.60 ea x 2 (14.00 list)
116 997 04 81 - a/c hose through firewall - NLA
116 997 10 81 - wiper cable to cabin - 2.53 (2.70 list)
116 997 22 81 - a/c hose RH - 0.90 (1.00 list)
116 997 00 81 - cowl drain hose grommets + a/c hose grommets - 1.35 x 4 (1.50 list)
116 997 16 81 - vacuum hose grommet - NLA
116 997 02 81 - grommet firewall - 3.78 (4.20 list)

I may have left one or more out, pls let  me know and if you could check the actual p/n's on the grommets installed in the car we can determine if this list is correct and what is missing.

Tks,

Joe



jbrasile

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #18 on: 06 February 2012, 07:30 AM »
Chris, I forgot to mention: BE VERY CAREFUL not to let any water into the evaporator so make sure you close up the tubes pretty tight.

Tks,

Joe

1980sdga

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #19 on: 06 February 2012, 09:00 AM »
I used some vacuum plugs from an assortment picked up at a parts store to keep my evaporator sealed.  If possible you could purge it with inert gas like argon and then cap it.

You'll also have to change the O-rings on the compressor manifold and they are different from r12 to r134a. The service valves will need to be addressed as well.

You may want to call around to some AC shops and see if anyone has the equipment to deal with r12. You may get lucky and find someone or you could find some r12 for sale and leak check/charge yourself.

You say your car wouldn't shut off  ;D
Jon


Little by little I have grown fond of the infamous Auto Temp II we have in our 116's

ckamila

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #20 on: 07 February 2012, 01:23 PM »
Update - ETR switch just needed to be pulled a little harder. Heater and evaporator cleaned up and waiting on the rust converter to dry and washed the main airbox housing. Moving forward with re-foaming lower vent flaps. Disassembled flaps and that sneaky vacuum pod. Off to the foam store to match existing before cleaning up


This is after removing the loose rust and applying rust fix 




Left vent coming out




Think i will use my heat gun to soften up the plastic to replace vents - really needed to bend the side support more than i like, but Major Tom made it without breakage. So far me too.




Vacuum pod is getting new diaphragm (from George Murphy) and rubber supply hose





Next up is the defrost vent foam - not sure how to remove flaps from control rod. These flaps do have 2 sets of 3 pinch connectors (old fashioned clothes pin) so that might be all that is needed to remove.





« Last Edit: 07 February 2012, 07:39 PM by ckamila »
If it's not broke i haven't fix it yet...


1980 300SD, 170K
1985 300D, 235K

1980sdga

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #21 on: 07 February 2012, 04:42 PM »
Wow! Great work!  Friggin' leg flap pod is buried deep  :o

Any ideas about what type of foam to use?  It looks as if they just used contact adhesive to hold the foam in.
Jon


Little by little I have grown fond of the infamous Auto Temp II we have in our 116's

jbrasile

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #22 on: 07 February 2012, 04:50 PM »
Chris, we are going to have to name you Mr. AutoTemp II !!!!! Very nice Sir!!!

I believe the foam used is pretty thin and pliable, it's function is to cushion the flaps when they close and seal the openings.

Tks,

Joe

ckamila

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #23 on: 07 February 2012, 07:23 PM »
You guys are TOO kind!

Without the forum for support and knowledge I would still be pressing my [DEF] button to shutoff my car ;D Of course that was when my car actually ran.

Just picked up some foam today (3mm or .125") but not sure if the cell structure is dense enough. Seems about half as dense - new foam has more open space than original but thickness is about right. This begs the question ...what is the purpose of the foam in the first place, sound deadening or sealing off airflow?

(edit - Sorry Joe, missed part of your post - eidt) Should i look for a denser foam or not a big deal?

Right vent flap foam comparison


Different angle


Bottom side of lower airbox tray connection to rear floor duct section - this 1/2" foam is just right, maybe a little denser but will work. Too bad they did not have any in 1/8"


Defrost vent foam comparison


Thanks,
« Last Edit: 07 February 2012, 07:43 PM by ckamila »
If it's not broke i haven't fix it yet...


1980 300SD, 170K
1985 300D, 235K

KenM

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #24 on: 08 February 2012, 02:07 AM »
Check with some a/c wholesalers Chris, you can buy rolls of foam tape with a sticky back in many widths and thicknesses, might be something you could use and stick straight on. I would be careful using a

heat gun on your plastic, if you stress it while it's hot it may not go back to the original shape. Just a thought.

Cheers,
Mexican girl: 'We could go for a walk outside and you can kiss me on the verandah'
Chevy Chase: 'On the lips will be fine'

3 amigos

jbrasile

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #25 on: 08 February 2012, 05:37 AM »
Chris,

The 1/2 inch gray foam looks perfect. The white one seems a little too open, try to find one with a little more density to it so you get a better seal when the flaps close. Ken made a great suggestion regarding the foam with adhesive back, should be easier to work with as long as the glue is strong enough to keep the material in place, remember that the foam can become humid due to condensation form the a/c system so it needs to be able to stay put indefinitely.

Tks,

Joe

Hemersam

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #26 on: 14 February 2012, 02:05 PM »
Since so many of you are responding to this work, let me toss in an anemic observation. The a/c/heat in my '78 280SE works fine (as fine as possible), but the drain from the heater/ac box stops up after using the a/c for very long; when I make a hard right turn, water pours down onto my accelerator foot. I'm told it's because the "pan" on the bottom of the a/c/heater box is stopped up. When the drain tubes are blown out by compressed air, things work for a short while, then here comes the water again.
I'm told it's necessary to get into the box itself and clean it out, which requires removing the center console and bottom part of the dash to get to it. I'm too old for this kind of project and have to pay to have it done. Is this the correct way to solve this problem, and if so, how many hours would it take a tech to do it? Any guidance here? Thank you.
Hemersam

ckamila

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #27 on: 14 February 2012, 03:13 PM »
Hemersam - Others will chime in but i would think 4 - 6 hours for someone who has done it before or similar jobs.

Sounds like dirt/debris and maybe old foam clogging up your drains - 2 i believe on the 78. I have 4 drains on the 80.

Another thought is that mud or dirt/oil mix is clogging the drain tubes from the outside.  Maybe the tubes themselves are failing, not allowing condensation to pass.

Things that need removal:
Pull the seats
Pull center console bits
Pull the lower dash and kick panel bits left and right
Pull the tunnel
Remove rear floor heat ducts left and right
Remove 4 clips (2 front, 2 rear) and slide out the lower tray/vent section

Chris
If it's not broke i haven't fix it yet...


1980 300SD, 170K
1985 300D, 235K

1980sdga

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #28 on: 14 February 2012, 04:03 PM »
I gained access to the drain hoses by removing the lower dash panels and gently moving the console "wings" Mine were plugged with rust colored pieces of foam.

The way Chris described would be best but man, what a lot of work!
Jon


Little by little I have grown fond of the infamous Auto Temp II we have in our 116's

ckamila

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #29 on: 17 February 2012, 07:33 PM »
Time to reverse the process....


Need to get that stuff off the dinning room table before my wife gets home  :o

   

Airbox consists of mainbody where evaporator sits, a framed section separating evap from heater cores, front section houses defrost vent flaps and the lower tray piece. I have installed new foam on the floor vent flaps, defrost flaps and connecting point between rear floor ducts and airbox lower tray. All airbox sections washed, heater and evap cores cleaned, rust inhibitor applied and painted with copper colored rattle can on hand. Still need to add new 1/4" open-cell foam around perimeter of both evap and heater cores to direct airflow through finned sections.

I have in hand a new replacement expansion valve (not installed yet) original  p/n 115 835 00 72.
(?)  Any sealing compound used on expansion valve flared (compression) fitting threads???


(?)  Regarding neoprene seal...this creates a water tight seal for condensation, should i replace with new? FSM states "replace cord," so i guess so. Total of 3 neoprene sections: pictured is longest and travels around bottom of the main body of airbox between center heater frame section and main body, separating evap from heater core , probably 18 - 24". The other two 5" sections are slightly higher up and separate front section from middle heater core frame - probably for noise reduction rather than water tight seal.




(?)  A/C hoses - buy new? Seems only one a/c shop in the area works with r-12.

Stopping by another (closer and in business since the late 80's) a/c shop i could not acquire the 1/4" dia. neoprene cord but they did give me 2' of cork tape for free ;D. They also suggested, as a friend had, to go to Northwest Air Conditioning in Seattle who can use my hose ends with new hose sections.
http://seattle.citysearch.com/profile/10806622/seatac_wa/northwest_air_conditioning.html

Thanks,

Chris



« Last Edit: 17 February 2012, 08:39 PM by ckamila »
If it's not broke i haven't fix it yet...


1980 300SD, 170K
1985 300D, 235K