^ this would explain why when I turn the A/C on, the coolant temperature starts going up. At idle before I did the aux fan modification to have it run all the time, it would go up very quickly towards 100C.

I will get some A/C flush, a new expansion valve and get it all clean.

Am I going to need to do the compressor too, or can I just flush everything else? Removing the compressor is a PIA.

Thanks guys!

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

Alrighty system flushed, gonna let it vac for 45mins or so just to be on the safe side.

Replacing the expansion valve was a little fiddly...but got it eventually.
Those black O-rings there just crumbled in my hand when removed. Probably being proactive killing any o-ring leak locations right now

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

Alright everything is sealed, its better, but its still not perfect.
Ambient: 102F
Low: 55psi
High: 310psi

Was pulling 49F from the vents on a 2mi drive, so I feel like its doing a great job. Maybe I'll just live with where its at.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

Sounds like normal limitations of a R134a converted system.

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

Wow! I missed your ambient temp on my first read. At least its a dry heat though right??!! lol..

A little late now but maybe you should have gone back with the r-12.

How much 134a did you put in? IIRC on a conversion you typically drop the charge amount by 8-10%. The 134a is not as forgiving as the r12 when it comes to charge amounts, especially on a conversion. I'm sure your well aware of this though. Have you tried any "coil cleaner" on the condenser? How's your fan motor? Maybe come up with a stronger motor; higher fan speed. Seems to me if you could get the high side down maybe to 270-280 ish; your low side would move more into an "acceptable" range.... I'm just babbling out loud.......

Pressures sound right.

EDIT: 2nd thought at 55PSI low end you might be overcharged.

try getting to 30 PSI on the low end.

rjp

__________________
03 540I (GAK!!)
81 280E (W123)
70 LeMans Sport with pissed off Poncho 462"
1989 Silverado Step Side (under the knife- complete restomod)

I put in 22oz of r134a do not overcharged. I think I'm just at the limitation of the conversion as said abovve.

Evaporator is original so I don't want to convert back to r12 in case it makes it leak.

This morning on freeway 92F ambient was pulling 39F from vents!!

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2008 Black Mercedes E350 4Matic Sport - 131k
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2003 Gray Mercedes ML350 - 122k

39 degrees under any circumstances is good.

rjp

__________________
03 540I (GAK!!)
81 280E (W123)
70 LeMans Sport with pissed off Poncho 462"
1989 Silverado Step Side (under the knife- complete restomod)

R12, won't make it leak. In fact it is less corrosive when combined with moisture than is 134. If the system has had PAG it would be mandatory that the entire system be flushed in a reverse conversion. If all it has seen is Ester, it would be a much easier reverse conversion.

Hope this helps.

__________________
2001 SLK 320 six speed manual
2014 Porsche Cayenne six speed manual

Annoy a Liberal, Read the Constitution

I am debating just outright replacing the condenser, BUT if I do, it makes sense that I replace it with the updated condenser used on the later W124's that is a parallel flow (PLUS its like $80 cheaper too!!)

Has anybody done this upgrade, and know if I can still use the single fan or is it REQUIRED that I use the dual fan setup?

EDIT:
Looks like part numbers for the lines are the same so no need to change anything that side. Does anybody know what I would need to fit the dual fan setup?






Also, just wondering can the condenser be removed from the front without removing the radiator?

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

Well the evaporator isn't clogged...no airflow restrictions or heating up.

















Blower motor got stuck due to the recent windshield replacement, but I managed to get it free without breaking either the glass or the motor...phew!
I think next step is the condenser replacement. Going to source everything I need to retrofit the dual aux fan setup.

__________________
2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

It was 113F today...with A/C working as hard as it could, on the freeway I was running at about 95C and once in the city, it worked its way up to 105C...

Is there anybody here on the forums that can compare engine temperatures /w A/C on in my ambient? I'm just struggling to figure out if this is just the M103 cooling system limitations, or if this is being caused by the elevated A/C pressures...

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2016 Monsoon Gray Audi Allroad - 21k
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2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

PS,

105 C is only 221 F. In extreme ambient such as you indicate, that's just not bad. As long as there are no pressure leaks, it is nowhere near boiling and is just not going to cause any trouble. Your cooling system is evidently in pretty good shape. You're in a tough thermal environment you know.

Also, earlier in the thread you asked about the condensor. Why are you contemplating replacing the condensor?

BTW, I wasn't aware that the late 124 has a parallel flow condensor, but that may very well be so. In the illustration, however, it doesn't look like one. Beware that parallel flow condensors can not be adequately flushed if the need ever arises. It makes them a throw away. The World is a compromise I suppose.

__________________
2001 SLK 320 six speed manual
2014 Porsche Cayenne six speed manual

Annoy a Liberal, Read the Constitution

I am just concerned that the elevated pressures are causing a viscous heat cycle. I am contemplating replacing the condenser (with the later model W124 PFC), the compressor (to be safe) and putting R12 back in after flushing all the lines and replacing the drier again.

Maybe I am just overconcerned and expecting too much out of this old girls system, but I don't enjoy starting the car when after 10mins of shutoff, it is up to the red line. Its very difficult to cool off once its at that point...and the A/C sucks as soon as the engine is that hot.

This is only of concern at anything over 100F ambient -- less than that and she will drive at less than 95C all day long including city traffic. Soon as it starts going upwards of 100F ambient, it progressively gets worse and she struggles to cool both myself and the engine!

__________________
2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

I've owned two 124 cars, an '87 TD wagon and an '93 2.8 sedan. Both cars in Dallas, so a little bit of summer heat. Based on my experience, your coolant temps are normal and not a concern. Both my 124 cars would run 90+ on the highway in summer heat. Both would reach 105 in stop and go driving, with the coolant temp slowly falling while driving at city speeds.

My opinion - you're obsessing over nothing.