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Parallel flow condenser

Started by 1980sdga, 29 June 2011, 07:50 PM


You're right about the oil Jon, if you have PAG already then you can go with either refrigerant, remember to flush the system if you are changing from mineral though (think you already had 134a from memory).

Thinking back to your pic of the grungy filter/receiver I'm sure you will notice much improved performance whichever way you go.

Squiggle Dog

Quote from: 1980sdga on 03 July 2011, 08:12 PM
Cool. Don't you have ACC?

I've removed some of the components of the ACCII and at some point will have a fully manual system.
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1967 W110 Universal Wagon, Euro, Turbo Diesel, Tail Fins, 4 Speed Manual Column Shift, A/C
1980 W116 300SD Turbo Diesel, DB479 Walnut Brown, Sunroof, Heated Seats, 350,000+


I really like the looks of the manual system. It just looks more like it belongs there than the ACC. I would like to experience the manual controls though. I've read that it works well.

I would also like to experience a working ACC system  :P  Mine was working 100% about 10% of the time  ;D 

My system was converted to 134a in 2001 according to the sticker and it was cooling pretty well when the flippers and flappers were working and the heater valve wasn't open  ::)

The service records show that it was recharged about every year and you guys saw my drier guts. I'm hoping new hoses will help with the leaking if I can assemble them properly  :o

How many cars had ACC and an R4 that were sold outside the US?  Seems like the Euros got most of the Sandens.



R-4's as far as I know were exclusive to OM617 engines.

Most euro's prior to 86 have York on 6 cylinder and diesel powered cars and A-6's on the V8-s

Starting in 86 you will see either Sanden or Nipodenso across the board. Some mid to late 80's cars equipped with M110 engines also got Sanden

The manual a/c system when working properly is far superior to ACC in all respects and having full control of temperature and air flow is just so much better.




Thanks Joe. That explains why all the 617 info (Including 126's, which are common here) is about R4's. There may have been some sanden brackets for 617's but I believe they were aftermarket and they seem to be awfully rare!


Some quick pics of the new condenser:


Looks like it will work!  This is still mocked up with none of the hoses crimped or anything. I still need to make a bracket for the cooler lines near the compressor but I'm VERY happy that it'll work with the stock cooler lines:

Here's a mockup of the condenser:

Kind of gives an idea of how much room is needed for the end hoses. They take up a lot of space  :o

I'm actually planning on taking Bolbols idea to the next level. He said he had good results with a similar compressor and an orifice tube. I figure a P-flow condesner can't hurt.

Any input on this one?

What do you think Ken?  Am I insane  :o


Hey Jon, in your first pic it looks like you won't be able to get a gauge onto to the discharge access fitting, unless it's the angle of the pic. Unless the condensor has internal channelling, having a receiver/drier will be important

otherwise you might find that you get flashes of vapour in the liquid line. Personally I wouldn't be in too much of a hurry to change to a fixed orifice type expansion mechanism, it's old technology from before tx valves became

much better. Whichever system you use, you can (should) only deliver as much refrigerant to the evaporator that can be successfully evaporated before it leaves the evap, otherwise you are asking for liquid floodback to the

compressor. With a fixed orifice the correct refrigerant charge of the system will probably become much more critical for this reason and with the variable flow nature of a vehicle a/c system due to compressor speed

fluctuation and variations in internal heat load the chances of flooding would increase. You would need a decent accumulator in the suction line to accommodate these factors. If your tx is adjustable you should be able to get

the superheat right down to 2 - 4k which will provide maximum cooling with less risk of flooding or oil return problems.

Just my $0.02.   


Thanks Ken. I'm not past the point of no return yet  ;D

The condenser has about 6 compartments in each tube. I looked inside to check and you can see them divided up. The tubes must be extruded aluminum.

It's just really different technology from the old one.  The volume I'm losing kind of bothers me. No receiver either...

I wonder if the new style condenser is that much more efficient than the old one?

Going to an orifice tube from an expansion valve  really just changes the volume of liquid for the volume of gas, right?  I was thinking about using a big GM accumulator like GM systems use to keep any liquid from reaching the compressor. 

Are there specific parameters for the high and low side pressures to go by when charging?  (I am having a professional vacuum the system and charge it if I ever get it done :o)

I have ordered a hose crimper, and I needed new hoses on my old system so If it doesn't work out well I can re-install the expansion valve. It'll add about $150 to the project to try this and it's interesting to fool around with.  I am going to test out the system before putting the instruments and all back in!

The mechanicals and all look OK. I still need to build an oil cooler line bracket above the compressor and all the access fittings have clearance.  It's hard to get a good angle on the pics because it's so low on the engine.  Making sure everything would fit and still be accessible was my biggest worry!

Thanks again for the help Ken! Your descriptions really gives me a better understanding about how these systems work.


Put a bigger fan on it. 16" vs the original 12". I got it at Advance auto and it's about the biggest fan that I could find that would fit in there.

I'm hoping it'll help the condenser work the way it should.

Done with this part:

I modified and re used the old aux fan mounts.  It's not that loud and moves a lot of air through the condenser.


Looking very professional Jon, nice work I'd say. That style of condensor is much more efficient than the tube type, it simply comes down to surafce area and the internal surface area is much larger than the old style ones,   

which is why your new one is so much smaller. A receiver/ drier will be a must in the system and definately get an accumulator if you are going to the fixed orifice type setup. Sounds like your weather is similar to ours here, in

reverse of course. We get filthy humid summers and lovely clear warmish winters usually, been a fantastic winter here this year so far. Not sure what you mean by 'Going to an orifice tube from an expansion valve  really just

changes the volume of liquid for the volume of gas, right?'  Both of them are simply a means of changing a high pressure liquid to a lower pressure liquid/vapour mixture so that it can evaporate in the evap and absorb heat.

The difference is that the fixed orifice is going to continue to hump refrigerant into the evap whether it's evaporating fully or not, whereas the tx will sense that it's cold enough (actually works around pressure not temp) and

close off accordingly. You will have to play around with the charge in the system in order to get it right, I imagine you might need to drop in a bit more oil too to compensate for the accumulator. The important thing will be to

check the superheat at the compressor, the fella charging it for you should know all that.

Looking forward to seeing the results. 


Thanks Ken! 

What I meant by "Going to an orifice tube from an expansion valve  really just

changes the volume of liquid for the volume of gas" is that:

TXV- uses a receiver which stores LIQUID refrigerant in order to ensure that the TXV has enough liquid to keep the evaporator flooded Kind of an extension of the condenser.

OT- uses an accumulator which stores GAS refrigerant which I guess is just an extension of the evaporator and ensures that the compressor has enough gas and doesn't get any liquid.

TXV- uses the valve to "throttle" the gas through the evaporator

OT (CCOT)- uses the compressor switching on/off to throttle the gas through the evaporator.

I'm trying to learn this stuff (Mainly for the heck of it) and I appreciate your input!

Here's my oil cooler line bracket:

I'm anxious to get it together and fire it up!



Here's my accumulator. It fit nicely into the spot where my cruise control servo was. I'll have to permanently move it if this works.

I also started working on mounting the receiver:



Jon, you are doing a beautiful job. I have couple of observations. With Orifice Tube system, the receiver/dryer is replaced by the accumulator. When I did my system, I took out the receiver/dryer and custom fit a connection piece after the condenser and just installed
the Pressure and temperature switches on this piece,, those are usually installed on the receiver/dryer in the original setup.

I tried to research the outcome if I kept the receiver/dryer and accumulator at the same time. I got no direct answer from anyone who is experienced in Auto/AC. Just the typical answer , "OT uses accumulator and TXV uses receiver/dryer" 

Ken, any input ?

Jon, in my opinion I see no reason why your setup will not work. The receiver/ dryer will work as an extra filter,reservoir and it Will do a better job at drying and filtering than an accumulator.  your high pressure side may get little higher, but it should not be a problem at all.

Now, with regards to the temperature and pressure switches, are you saying you did not have those originally ?

One more thing, with your Parallel flow condenser and fan installed, you might notice that coolant temperature will get higher, but I don't think you should  worry about it.