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Installing new system in a classic Mercedes,, Question about condenser, Pictures inside .

RichC on Wed August 06, 2008 7:39 AM User is offline

Year: 1982
Make: Mercedes Benz
Model: 200D Euro model
Engine Size: 2.4
Refrigerant Type: R12 hopefully
Ambient Temp: 112
Pressure Low: none yet
Pressure High: none yet
Country of Origin: United States

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Hello everyone .

I am new here, just found the forum, so I thought I would tell you guys what I am up to. And ask for suggestions.

We are putting an AC system into an old 1982 Mercedes we are restoring.

So far we have a Sanden 805 compressor and bracket.
The factory evaporator and expansion valve.
An aftermarket accumulator / receiver drier.
And an aluminum condenser from a 1996 Camaro. (largest we could fit in the space we had)

I have a question or two about the condenser.
Is there a way to tell if it is a parallel flow type of condenser ?
And is there a way to tell which is the inlet and outlet for the condenser ?

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Do you guys like the Sanden 805 compressor ?
Any other tips, tricks, or comments would be appreciated.

....

I can provide some pictures if you guys want to see them.

....

Thank You
Have Fun !
RichC

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I think I will quit calling this a project

And start calling it an adventure

Edited: Fri August 08, 2008 at 10:19 AM by RichC

johnboy123 on Wed August 06, 2008 8:56 AM User is offlineView users profile

The sanden is a good compressor and will give you good service - flush the condesor to clear it of any debree and old oil that may have collected in it - the top of the condeser is where you hook your line coming off of the compressor (high side) the bottom line leads to the expansion valve - hot gas from the compressor start at the top of the condensor travels through it cooling forming a liquid - add your pag into the compressor low side and turn the clutch by hand until the oil is coming out the high side - recap the compressor until ready to install and add lines to it - Next decide what refrigerant you are going to use. Since you your system will be operating off an expansion valve either refrigerant will work equally well. The primary difference between the two refrigerants will be the oil you use and the amount of refrigerant that will be required to operate you system efficiently. Personally i would recomend the R134A and the pag oil, go with the pag 46 - The amount of oil you will need as a rule of thumb is 2 oz for the condensor, one oz for the evaporator core, one for the lines, two for the accumulator if it is the gm type (note the compressors generally come with the instructions on the amount of oil they require generally 6 to 8 oz) next, i would recommend that you add dye to the system it is the easiest way to check for leaks by using a black light. Now comes the tricky part - since i don't know what equipment you have available to you and because you are building a system is the amount of refrigerant that will be required. So i will start with the proceedure i would use - first, i would have added the needed amount of the pag to the accumulator and recapped it until i installed it and it would have been the last thing i installed on the system. Then i would evac the system for a few minutes and see if it would hold the vac that would give me the first indications of any leaks - if the vac held after a few minutes - then i would add a small amount of refrigerant (to move the ncg's (air) around in the system and evac for about an hour depending on how much humidity (it can get very humid here) next, i would put in refrigerant until my pressures equalize on my guages or just a little short of equalizing (load your system from the low side only - repeat low side only - set my blower motor fan speed the next lower from the high setting - sorry but going to have to back track a little bit - what are you using for you pressure switches? - i am guessing a tritary switch (high/low single pressure switch) regardless you need at least a low pressure switch in the system to protect your compressor. start the engine and turn on the air conditioner - the ambient temperature (outside air) will be a factor in you pressures - lets start with 80 degrees ambient. (the higher the ambient the higher the pressures and visa versa) run it for a few minutes to let the compressor transfer the oil out of it though the condensor and on to the evaporator core and the refrigerant will be transfering oil back to the compressor from the accumulator. stick a thermometer into the vent closest to the blower motor - the pressures we are looking for is between 25 to 40 psi on the low side (depending on the type of low pressure switch) and 180 to 210 on the high side) if your compressor is cycyling off add more refrigerant until it stop cycling. what the goal is - at 1500 rpm's (this simulates 30 mph which is what it is designed for) 20 to 40 psi on the low side - 180 to 210 on the high side and a vent temp of about 40 degrees or a little less. that will give you the amount of refrigerant required for you new system. good luck

RichC on Wed August 06, 2008 11:13 AM User is offline

Thanks for the advice.
Much appreciated.

The pressure switch we are using is the Mercedes OEM.
I am not sure what kind it is but I do know it is adjustable, and just a low pressure cutoff type I believe.

About the condenser inlet and outlet.
I am not sure which is the top or the bottom.
And I am not positive that it is from a 96 Camaro.
We scrounged around until we found a good looking one that we could just barely shoe horn in the front of the car.
So I am still not sure what is the inlet and what is the outlet, or if it is a parallel flow type condenser.
If it was not a parallel flow I don't think it would matter how the condenser was connected.
But if it is a parallel wouldn't hooking it up backwards dramatically reduce its ability to condense ?

Maybe I should take some pics of the condenser and post them.

Thank You
Have Fun !
RichC

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-------------------------
I think I will quit calling this a project

And start calling it an adventure

iceman2555 on Wed August 06, 2008 10:55 PM User is offlineView users profile

Check the Camaro condenser very carefully....some of these units are a REVERSE flow unit. May not work with the MB.

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

RichC on Fri August 08, 2008 10:11 AM User is offline

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I took some pics of the condenser.

Had to take one of the car so I could show it to you.

This first one is the side of the condenser where the connections are.
I am not sure if I have the condenser upside down, or right side up.

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The next two are the condenser in and out of the car.

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And this last one is the car we are working on.
Pretty little thing isn't it.

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Do you think this condenser is a parallel flow one ?
Which connection on this condenser goes to the pump ?
I'd hate to fab all the brackets and get it in, just to find out I had it backwards.

Thanks again.
RichC

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I think I will quit calling this a project

And start calling it an adventure

Edited: Fri August 08, 2008 at 10:16 AM by RichC

HECAT on Fri August 08, 2008 10:36 AM User is offline

It appears (from the picture) to be a 2 pass or 4 pass parallel flow condenser. Without the opportunity to inspect closer, I would say it would work in either position. Although there may be some subtle differences in the inlet and outlet chamber designs that would make it best in one position. Compressor (High pressure, hot gas) inlet will be the top port.

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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

steve325is on Fri August 08, 2008 2:32 PM User is offline

According to the parts 'splosion, you have it in the orientation that it was in for the Camaro.

-- Steve



HECAT on Fri August 08, 2008 3:19 PM User is offline

Iceman,

Is this the REVERSE flow you eluded to?

I ask because this diagram is showing the outlet at the top going to the Dryer (#2), is it not?

This is the first I have seen of this, just when you think some basics will remain the same.

Was it because it lays back at such an angle in this body?

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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

iceman2555 on Fri August 08, 2008 3:29 PM User is offlineView users profile

This is a reverse flow unit. As a point of interest, I would be concerned when mounting this is in a conventional flow pattern.....discharge in top....liquid out bottom.
The normal flow pattern of these units is a more tubes/larger surface area in the inlet area and a smaller/less tubes in the liquid (outlet) section. With the cost of these units been so low...why take the chance of possibly destroying a compressor....why not simple locate a condenser (universal) that will work with this system for a normal refrigerant flow path.

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

RichC on Fri August 08, 2008 7:07 PM User is offline

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I do not know enough about ac systems to understand what a reverse flow condenser is.

I am very new to ac work.

That is part of why I came here.

I am quite willing to learn,
point me in a direction and I will go read.
Or try my best to understand what you are saying.

Please excuse my ignorance on the subject.

Thank You
RichC

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-------------------------
I think I will quit calling this a project

And start calling it an adventure

HECAT on Fri August 08, 2008 8:50 PM User is offline

The normal, traditional, conventional and most common flow into a condenser is with the compressor discharge (high pressure hot gas) in at the higher port, with high pressure (condensed) liquid out at the lower port; in a TXV system, this outflow goes to the filter/dryer next.

Looking at the diagram for your condenser donor, the outflow is at the top. Unfortunately you have selected the proverbial "one in a million" oddball system to rob a part for your project.

I already envision the challenges of "dialing in" all the quantity, operating, and performance issues that come with building your own system. Since you have voiced this concern; "I'd hate to fab all the brackets and get it in, just to find out I had it backwards." I would agree with Iceman; you will be time and money ahead to see if one of these will fit.

universal parallel flow condensers



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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

iceman2555 on Sat August 09, 2008 12:09 PM User is offlineView users profile

Rich no need to apologize for 'not knowing'...heck...we all learn something each day...
I use a photo of this system in my training classes....and believe me....there are very few 'seasoned techs' that pick up on this.
HECAT...not use why GM decided to go with this condenser design...some of the vehicles in this series used a 'reverse flow cooling' system....but the 3.8 seems to have a standard coolant flow...have to check when my son returns....open the hood and check it once more. Can understand if the entire cooling system was reversed...but with a standard flow rad...and a reverse flow condenser.....???
Did speak with a GM HVAC engineer and he stated that the flow...gas to liquid...was not disrupted by this manner....states that the flow is so rapid that there is no problem with gas pushing liquid upwards.....I did ask if the angle would contribute to this 'flow' being acceptable...and he did not have a firm response. I wonder if the condenser were mounted vertical...would it still not have a problem with flow.....hence, my suggestion to obtain a 'standard' flow universal unit.

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson



Edited: Sat August 09, 2008 at 12:09 PM by iceman2555

RichC on Sun August 10, 2008 4:46 AM User is offline

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Dang, dang, dang. Just my luck.
And this condenser fits so well.

Could I flip it upside down and still use it ?

Thank You
RichC

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-------------------------
I think I will quit calling this a project

And start calling it an adventure

iceman2555 on Sun August 10, 2008 6:16 PM User is offlineView users profile

If this is the unit that is going to be used....then....at least to my mind....flipping the unit would make the most sense. I cut one apart yesterday....and seems like this flow patter would work as any conventional condenser. I am just not sure of the flow when mounted in a 'normal' position...esp since the liquid side (outlet) side of the condenser is connected to a system where this becomes the discharge (gas) inlet side. The inlet flow of the condenser in this configuration would be approximately 1/2 the volume as a standard flow unit. Not sure if that made any sense or not....but in my mind....the picture is perfect.
If the hose assembly will fit and not be a hindrance....go for it.

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

RichC on Mon August 11, 2008 6:35 AM User is offline

.

I think I understand what your saying.

If I flip the condenser it should work ok.

If I use the inlet and outlet reversed I will be halving the flow thru the condenser.

But if use its inlet (gas), and outlet (liquid), the way they were intended to be connected
(the way they were connected on the original vehicle the condenser was from)
I should not be halving the flow.

And I should have a normal pattern.
Gas inlet at the top, liquid outlet at the bottom, with no flow restrictions.

Ok, I will try It.

I will get back with you on how it works

The worst that could happen is that it takes the compressor out.
And that would give me an excuse to get a new one.

Thank You
RichC

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I think I will quit calling this a project

And start calling it an adventure

TRB on Mon August 11, 2008 10:39 AM User is offlineView users profile

This is why I love this site. This is the first reverse flow condenser I have seen but I don't work on many Mercedes. Guess I can no longer state the large line always on top!

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iceman2555 on Mon August 11, 2008 9:18 PM User is offlineView users profile

Actually the condenser is for a late model Camaro. Not sure why it was designed as a reverse flow unit..unless it has to do with the reverse flow cooling of the earlier V8 engines. This is actually used on the base 3.8 6cyl. However, it is a bit strange to see the gas side on the bottom......but seems to work. Did some temperature test on my son's vehicle.........and it works like a charm.
TRB, had another trip to your area on the schedule for next week, however, seems as if that is going to be changed. Was looking forward to a great dinner.....still got Dallas this year for MACS!


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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

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