Photo step by step post showing a W123 evaporator removal (1983 240D and 1982 300TD) - PeachParts Mercedes-Benz Forum

dmorrison · #1 06-17-2006, 11:53 PM

These pictures are from replacing the evaporators in my Daughters 1983 240D and my 1982 300TD. Not every little step is included. As you progress you will figure things out. This is not a terribly difficult job. Just time consuming. AC knowledge is required for this job and a 609 license is worth while. Not mandatory but preparing for the test teaches you a tremendous amount about the AC system.
Notice some pictures are labeled 300TD, 240D and 300TD/240D. I am trying to show pictures that are specific to the model listed. IF I have not listed a car then it applies to both. What is specified for the 300TD will apply to the 300D and 300CD usually. This is for a “Automatic Climate Control III” for the 300TD as specified in the Mercedes Service Manual. And the “Heating/Ventilation and Air Conditioning I” as specified the Mercedes Service Manual for the 240D. The only difference in the 240D system is the car has the R-4 compressor not the York unit shown in the Service Manual.
Of course disconnect the battery, drain the radiator and you will have to recover any freon in the AC system.

Note, when looking at the pictures if the car is maroon in color it is the 240D. Signal red ( stop sign red) it is the 300TD

Any recommendations for this post will be appreciated.

Dave

I have edited this post to make corrections so that the names of various parts match the Service Manual name, and a few spelling corrections

Page 1

dmorrison · #2 06-17-2006, 11:54 PM

001 Remove Mercedes symbol, this is not really necessary.
002 Peel the horn cover off
003 Pull the center of the cover off hub
004 After removing bolt, Mark the shaft wheel relationship with a punch.
005 Remove ashtray

Page 2

dmorrison · #3 06-17-2006, 11:54 PM

006 Remove center console carpet and remove screw
007 Remove ashtray bracket mounting screws
008 Lift front of wood trim above shifter and slide to the rear to remove
009 Disconnect wires
010 Slide towards rear to protect the pin, disconnect switch wires

Page 3

dmorrison · #4 06-17-2006, 11:54 PM

011 Pull radio
012 Label radio wires
013 Pull off AC control knobs
014 Use socket to remove AC control nuts
015 Pull AC panel and disconnect light units

Page 4

dmorrison · #5 06-17-2006, 11:54 PM

016 Pull switch out from the rear
017 Pull all switches and remove the wire harness
018 Using your fingers in the outside holes, push the wood trim out from behind
019 Wood trim lifts at bottom first then out
020 Disconnect the temp dial wires using your fingers. 2 harnesses

Page 5

dmorrison · #6 06-17-2006, 11:54 PM

021 Push in the top tab and remove the dial by pushing the unit into the console
022 300TD/240D. Remove the outboard switches to remove the screws
023 Remove both front seat inboard slide bolts in rear tunnel
024 Remove drivers seat back panel. Unscrew it then slide the panel down.
Or remove the entire driver seat.
025 Remove the bolt holding the drivers seat armrest

Page 6

crazy4diesel · #7 03-28-2014, 09:26 PM

I don't think that Dave the OP of this thread, has logged on since last October, but I'm wondering if anyone knows if the broken bracket he describes in this wiki is available? Mine is also broken, it has a part number on it of 90 412 09 127 which I am not able to locate anywhere.

vstech · #8 02-26-2016, 12:45 PM

black death is microscopic aluminum particles mixing with the oil and bonding to the metal and rubber tubing. a liquid filter can trap the particles with all the dessicant surfaces of the filter media. the screen and mesh in the casing keeps the scrubbing action of the liquid in place. with gasses you only have the surface area of the screen to catch what passes through. they will certainly catch some stuff, but the liquid side will catch far more. to be effective on the vapor side, the filter would need to be the size of our air filters to function well. notice there are only two types of filter driers for refrigerant. Liquid, and suction... the suction side filters are to protect compressors from building up contaminants in the oil, and to break down acids that form. they are HUGE in comparison to the liquid filters, and they only have about a month of life in them before they need to be removed, or they plug up, and kill the compressor.

sure, a liquid filter would offer some protection from black death or debris entering the condenser... but a liquid filter scrubs the oil and refrigerant for the life of the system, and prevents it in the first place.

leathermang · #9 02-26-2016, 07:24 PM

Quote:

Originally Posted by vstech

agreed... but keep in mind... a clean evaporator will increase the load on the compressor and condenser... so like I said EVERYTHING needs to be clean. .....

A clean evaporator does not increase the load on the compressor and condenser.... were you typing too fast when you wrote that? you can correct that and delete this post if you want to...

For the same amount of cold going to the passenger compartment having a clean and thus proper functioning evaporator is the minimum and designed load by the engineers for a given heat load...
any lack of cleanliness or obstructions increases the load and run time of the compressor.

vstech · #10 02-26-2016, 08:27 PM

Quote:

Originally Posted by leathermang

A clean evaporator does not increase the load on the compressor and condenser.... were you typing too fast when you wrote that? you can correct that and delete this post if you want to...

For the same amount of cold going to the passenger compartment having a clean and thus proper functioning evaporator is the minimum and designed load by the engineers for a given heat load...
any lack of cleanliness or obstructions increases the load and run time of the compressor.

I see what you are thinking, but the better the heat transfer through the evaporator, the more heat entering the refrigerant, and the higher the suction pressure will be. The txv will alter refrigerant flow to allow a set superheat be PRESSURE will rise with a clean evaporator coil.

vstech · #11 02-26-2016, 10:54 PM

Quote:

Originally Posted by leathermang

A clean evaporator does not increase the load on the compressor and condenser.... were you typing too fast when you wrote that? you can correct that and delete this post if you want to...

For the same amount of cold going to the passenger compartment having a clean and thus proper functioning evaporator is the minimum and designed load by the engineers for a given heat load...
any lack of cleanliness or obstructions increases the load and run time of the compressor.

let me try this...

a clean evaporator will impart more load on an ac system than a dirty one will...

better?

of course it won't bring more heat into the system than the system did when new... nobody has a new 123 ac system that I'm aware of on this forum...

lol!

also... there is no "cold" being put into the cabin... HEAT is being taken out of the air and it's returned to the cabin with less heat in it... that heat that is taken out of the air is drawn INTO the ac system. and the heat is pushed into the compressor by the evaporation pressure, and compressed by the compressor, and ejected from the system at the condenser. more evaporator clean surface area, allows more contact with warm air, and more heat enters the lines, and the refrigerant builds more pressure from it.

leathermang · #12 02-26-2016, 09:17 PM

Vstech, for the SAME amount of cooling output into the passenger compartment per period of time... a clean evaporator will be less work for the compressor....
You are not taking into account the fact that the compressor will cycle off when the ' pilot set temperature' is reached....

vstech · #13 02-26-2016, 10:21 PM

Quote:

Originally Posted by leathermang

Vstech, for the SAME amount of cooling output into the passenger compartment per period of time... a clean evaporator will be less work for the compressor....
You are not taking into account the fact that the compressor will cycle off when the ' pilot set temperature' is reached....

think about it... a dirty evaporator will ice up, it will block airflow, and it will take much longer to cool the cabin.

with it clean, the system will absorb heat from the cabin much quicker, the system will cool better, but that rapid heat absorption has an effect on the compressor and condenser, via the pressure rise.

the COMPRESSOR is happy with a dirty evaporator... but it won't cool very well. when the evaporator is cleaned, and the txv is operating optimally, with proper charge quantity, and a clean condenser, the overall system is much happier.

it's a total system, changing one part affects the entire system, not just the changed part.

many times techs will say, the pressure is low, it must be a restriction... but a restriction will cause the head to climb... no... a restriction will cause the head to drop. because refrigerant will back up behind the restriction. everything affects everything...

vstech · #14 02-26-2016, 09:55 PM

you are not taking into consideration that a clean evaporator will cool the cabin better...therefore, it will absorb more heat... the evaporator temp will be higher, the freeze switch will not activate, due to the higher amount of heat intake of the evaporator... that heat will cause more stress on the compressor and condenser.

if the condenser is not clean, straight, and ready for the excess heat... the lifespan of the compressor will not be long.
running the electric fan will assist with heat removal, but CAPACITY and SURFACE area are needed to reject it all.

leathermang · #15 02-26-2016, 10:04 PM

Vstech, To suggest that putting an ' obstruction ' to efficiency ( clogged fins on the evaporator) into a system designed for a certain working pressure and time engaged is harder on the compressor ( it was DESIGNED for that ) than a properly cleaned system does not make sense...
IF what you are saying is correct in the larger picture... they would have installed the dog and cat and human hairs on the input side of the evaporator at the factory....

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