Author Topic: ACC overhaul - Heater box / evaporator removal  (Read 25383 times)

ckamila

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #45 on: 25 February 2012, 08:56 PM »
Question, are there 2 different expansion valves available: R-12 and R-134a?

This link shows 2 different valves with the original part # across the top, while the second valve has R-134a on top. I purchased the original style R-12 I assume given the part #.

http://catalog.peachparts.com/ShopByVehicle.epc?q=1980-Mercedes--Benz-300sd-Climate--Control&yearid=1980%40%401980&makeid=63%40%40MERCEDES+BENZ%40%40X&modelid=6204%3AED|10000133%3AMBC|1509%40%40300SD&catid=242213%40%40Climate+Control&subcatid=242233@@A%2FC+Expansion+Valve&mode=PD


R-134a                                                                   R-12

                 


Also picked up a new Receiver/Drier and Behr compressor where it clearly states "R-134a only." I thought type of refrigerant used depended on type of seals and oil. Is there a specific R-12 or R-134a compressor? Please excuse my ignorance on all things a/c.... ???   Maybe it's time to pass off the ac stuff to the pros as i am swimming in murky waters with  R-12 this and R-134a that.

Behr info:
620230
QTY 1
20110218
8FK 351 316-221


thanks

chris
« Last Edit: 26 February 2012, 09:53 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 #46 on: 26 February 2012, 05:22 AM »
Which refrigerant are you going to use Chris? You won't be able to use a R12 compressor with 134a, the drier won't matter and you will probably get away with a 134a tx valve on R12 but the compressor

won't do. I thought the compressors were the Fridgidaire A6 type, haven't seen a Behr one before.
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ckamila

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #47 on: 26 February 2012, 10:30 AM »
KenM - OK, coolant refrigerant and compressor MUST match. Got it (finally). 

What refrigerant will i use....R134, i think.  ??? The R12 seems to be a big hassle and waste of time/money as the only shop working with R12 is 30 miles away, which only offers clients first come first serve type of service. They are the best shop in t he Seattle area and i might need to go there anyway as they also "have all the equipment to create new hoses from my ends" - at least that is what another a/c shop stated which has done a/c work for 20 years but no longer does R12.

you will probably get away with a 134a tx valve.....

I thought the compressors were the Fridgidaire A6 type, haven't seen a Behr one before.

Ken I assume from your statement and the posted link there is a specific a R134 valve to match the R134 system. Is the valve less important in the overall picture? Seem to recall Joe using his original R12 tx valve in a R134 converted system. I have the chance to match everything and easily replace questionable parts/hoses. I have a new tx valve with original part # so i believe that must be a R12 so i would want to exchange it for proper match, yes?

This Behr looks to match the original in size and shape, while the A6 is much longer. This new compressor is for the 300SD. I believe the other non diesel 116's use the A6.

              R4 compressor                                          A6 compressor

             

thanks

chris
« Last Edit: 27 February 2012, 08:02 AM by ckamila »
If it's not broke i haven't fix it yet...


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

ckamila

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #48 on: 26 February 2012, 10:52 AM »
Question - In a properly a/c system without leaks, be it R12 or R134, how long before the system would need some form of maintenance like additional refrigerant? This might help with the overall debate or refrigerant type.


thanks,

chris
 
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 #49 on: 26 February 2012, 11:53 PM »
I forgot that the diesels have a different compressor from either the 6 or 8 petrol engines. If you're going with 134a I think that's the best idea Chris, certainly if you have the opportunity now you should get a

134a tx valve while you have gone to all this trouble. Hoses as you say can be remade, make sure they use barrier hose. Once the system is running, I would imagine a drier change would be in order after

100 hours or so running time and then provided the system is tight you should not have to top up the charge for many years. A good and thorough installation is the key to reliable and trouble free system

operation, or certainly a very major factor.
Mexican girl: 'We could go for a walk outside and you can kiss me on the verandah'
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jbrasile

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #50 on: 27 February 2012, 03:12 PM »
Hi Chris,

If you are converting to 134 then make sure everything matches including the tx valve, the valve will be marked 134A. Your compressor is actually a Delco R-4 which is now made by Air Products. The rec drier is not gas specific as Ken said but if you ever consider going back to R-12 then it must be replaced.

Since you have the whole thing apart this is the time to get the correct Tx valve, it will make a difference in the system's performance. I did not replace mine or the hoses and have had no leaks in almost 2 years.

A tight system that is properly charged and used regularly will last a very long time.

Tks,

Joe

ckamila

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #51 on: 27 February 2012, 08:09 PM »
Hey Joe - there seems a constant stream of questions on this subject for me of course and truly i need to start moving forward on this project. Joe, beautiful job on that 1970 300SEL restoration!


What about the high and low side valves? Wouldn't they need to be the newer 134a type as well. Would the a/c shop replace them or is that another purchase? I assume the valves are removable.

As for the compressor i'll take your word for it - you da man, but that picture was taken from a web site to show Ken the difference  trying to share what little knowledge i have ;D or not  :-X . Mine is shown below.

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 #52 on: 27 February 2012, 11:07 PM »
You will need different access valve fittings with 134a Chris, you can get adaptors to fit on an existing R12 fitting or you can get them as part of a new elbow or straight section that attaches to hose. You also

need different adaptors for your gauges to connect to the system, the 134a type clip on like an air line fitting.

Some info here could be useful.

http://www.highgateair.com.au/images/stories/products-pdf/Compressor-Spares.pdf
Mexican girl: 'We could go for a walk outside and you can kiss me on the verandah'
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jbrasile

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #53 on: 28 February 2012, 05:39 AM »
Hi Chris,

Cool you got a Behr compressor! I did not know there was a version of the R-4 made by them, the design is originally from GM / Delco.

As Ken said, once you convert the shop will install adapters to your hi and low pressure fittings so they can hook up the 134 machine to it. Since you are having new hoses made, I would probably replace the valves at the same time, makes for a much cleaner look and you are assured to have all new parts an no chance for leaks from the old valves.

The 300SEL is going slow right now.... I need to finish a Corniche Coupe that is giving me the fits.... once I am done it will be 6.3 all the way to the end, plan is to deliver the car around July.

Tks,

Joe

ckamila

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #54 on: 28 February 2012, 07:03 AM »
Thanks Ken and Joe.

Since i will assemble and install airbox prior to dropping off at a/c shop, should i flush the evaporator with some chemical now to remove oil/contaminants  while evaporator is out and tx valve is off or have shop do it with tx valve on? How large is the diameter of 134a tx valve orifice? If i flush any recommendations on brand or type of chemical or those to avoid. I just want things done the right way regardless of who does the work.

Anything else you guys or anyone have for additional input of items not covered?



thanks,

chris
« Last Edit: 28 February 2012, 08:01 AM by ckamila »
If it's not broke i haven't fix it yet...


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

jbrasile

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #55 on: 28 February 2012, 07:56 AM »
Chris,

I really don't know what the shop uses to flush the evap, maybe you can ask them and see if you can do it yourself. Otherwise just let them do it and you should be fine.

Looks like you've covered everything, one last thing to look into is the operation of  the aux fan. I would recommend  you have it connected so it comes on together with the compressor, this will make sure your engine always stays cool and it will help increase condenser efficiency by lowering its temp and help compensate the slightly lower performance of 134 in these older systems.

Tks,


Joe


ckamila

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #56 on: 28 February 2012, 08:19 AM »
ETR switch connections - After having another look at the wiring diagram I see many of the other switches don't have terminal #'s listed so i guess the answer is no it won't matter which wire connects to which terminal as this just creates a connection between point "A" to point "B"

_________________________________________________ _________________________________________________ _________________________________________________ ____________
Original question - While removing airbox i missed disconnecting/observing ETR wire locations.  I have a original ETR switch and new replacement. FSM schematic shows one wire connecting from ETR to #18 (double contact relay) while the other wire connects to #25 (pressure switch) but don't' see which wire goes to which terminal. New switch has terminals #4 and #3 opposite end of probe wire while original has 2 terminals on top but don't see and markings.

Since this is a switch in either open or closed position will it matter which wire goes where?
_________________________________________________ _________________________________________________ _________________________________________________ _______________



http://handbook.w116.org/Climate%5C83-605.pdf

thanks,

chris
« Last Edit: 29 February 2012, 07:21 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 #57 on: 29 February 2012, 03:43 AM »
Flushing the system is best left until last Chris, or at least until the system is complete and won't be modified again, BUT, you must remove the tx valve and replace it with a section of hose or pipe. Do not

attempt to flush the system with the tx in place, you will just fill it up with crud and it will be ruined. Same goes for the compressor and drier, bypass them and pump the solvent around the system, then

evacuate the system to remove all solvent before refitting components. Probabaly best to leave it to a shop as long as they know what they are doing. I must admit I have never seen the point of wiring the

auxillary fan on all the time, 100 degrees is 100 degrees regardless of the refrigerant in use, the pressure differences between 12 and 134a are pretty small really so the effect should not be that great. Joe

has probably much more experience than me of driving a 116 in traffic though, so l stand to be corrected there.

Cheers, 
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Chevy Chase: 'On the lips will be fine'

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1980sdga

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Re: ACC overhaul - Heater box / evaporator removal
« Reply #58 on: 01 March 2012, 05:18 PM »
I flushed my evaporator with some commercial cleaner. It had a citrus smell and removed a good bit of crud from the tubes!

There are also some oil issues. The R4 was designed for ester oil or mineral (I believe) and R12. If you switch to R134a you'll need PAG oil and the volume is important because of the radial design of the R4. It has no sump so it relies on circulating oil for lubrication more than other types.

If at all possible I'd stick with R12.  That way you can use the oil the compressor was designed for.
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 #59 on: 07 May 2012, 02:48 PM »
Update: Well it's been a long time since posting...i got a little side tracked and did a few other things and found it's FAR easier to disassemble than re-assemble. Airbox now re-installed and just sorting out center dash wiring and vacuum lines. some lines still have a little oil from t he past which i will flush with solvent and compressed air. My #26 wiring connector is not clipping into the male section - not sure what's up - so i might just use wire ties to secure in place. Since this is just a switch and the connector appears to go either way i assume it can. #27 connector is facing with keyed (cut a-way) section towards valve, while #25 is the other way round as that's how i connected them.


Jon - i did/will end up with R12



  [size




Found a trick on the center vent side clips. Joe originally stated only needed the back clips and the rubber boot section would hold it in place. Well trying to connect the back clips is tough by itself since you can just barely squeeze your hand through the cut out section and then blindly press clip in. My though is i would loose the back clips too...so i tied a section of dental loss to both side and back clips to retrieve when they dropped. Once in i just snipped the excess.
 


Other items:
repainted air cleaner, metal water lines, brake booster, master cylinder and head light covers
wash out all sections of heating/cooling system duct work and vents
dealt with a little bit of rust
disassembled wiper fluid pump, cleaned, painted rusted bracket, installed
new battery tray - old one rusted through causing other surface rust issues in front right section (LHD)
replaced all the rubber 3 and 4 way connectors and rubber connecting sections
new servo and blower brushes from george murphy
rebuild blower housing and installed new foam on flaps
cleaned carpets
installed new grommets and other bits i received from Joe - Thanks again!


To do:
finish current project items - install blower, servo, a/c compressor along with drier
install new vacuum pump
install new motor mount pads and probably at least one engine shock and top shock mount




hey, joe - that new replacement grommet for the NLA part fits great! Just trimmed the opening a little.







thanks for all the help!


chris
« Last Edit: 08 May 2012, 07:13 AM by ckamila »
If it's not broke i haven't fix it yet...


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