OK

Good
By cooler, I assume you mean the temp gauge on the dash..correct?

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A Dalton

Yes the temp gauge and it felt cooler in the car.

OK

Now , one more test.
I think you can handle this one cuz we will be revisiting an earlier post.

That OTHER sesnor that I had you jumper with the 6" pigtail wires on it [ over at drier].

I want you to slip the insulation back at the connections of those 2 pigtail wires and jumper across there with a wire [ or you can unplug the pigtail and plug a spade fuse in its place as a jumper.
That will give you a constant low fan [ which is where this whole mess stsrted at].
Plug the high fan blu sesnor back in and try the car with this low fan set-up. Also try the a/c and that line you know gets cold and tell me what we have, both ac wise and temp gauge ...

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A Dalton

High speed fan works better than low speed. The 2 pigtail wires offered constant cycling, but was not as great as having the blue sensor unplugged....the temp gauge elevated with the 2 pigtails jump running at constant low speed. So I left those as is and unplugged the blue sensor again for high speed aux fan. The steel pipe is still not getting cold like it used to. It has a nozzle of some sort sticking out of the side...like on a tire to add air to it

The steel pipe problem is cuz you are not listening to my test.

I wanted ac report with constant low fan...but you decide to unplug for high fan...well guess what? you default ac when you default high fan.

These are specific test, so just do what the test call for.
we already know the temp dropped with high fan, we are now trying to establish ac operation w/low fan...and then I will tell you what to do

Do low fan test again and see if the ac is better and yout "STEEL PIPE" is working again

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A Dalton

I did do the ac low fan test again and its not as cold as with the high fan on. Its like going back to the very beginning when I firsted posted the thread. Its no different from then. And the pipe is not cold its warm

OK

So , the higher fan helped to some degree.

So , your orig question was is there anything you could do to help get better cooling and less over-heat..

The ac cooling will be the hard one b/c of the 134a system...Should have stayed w R12..but the engine temp can be checked a bit and that will in effect help the ac system.

Here are a few simple things that will help both ac and over-heat temps:

You can bridge the blu sensor with a resistor to make the high fan come On at a lower engine temp ..you are just lowering that sensors fan cut-in temp, getting a high fan before the coolant starts to rise b/c of your high ambient temps and climate. This works well and is cheap MOD to do.
ARCHIEVES [ or you can buy a ready made one from JIM F. here]

You can change your thermostat to a lower opening temp one ..fairly simple.

You can change the ratio of AF/H20 to 40/60 ratio. That will help slightly.

And you can add a cabin sw to allow activation of the low fans manually . BY addinga relay to that circuit, you can also up the low fan speed to high for the ac operation. A little tricky , but anyone familiar with relays would find that easy.
B/c your suction line is not as cold as it was , I also would have the refrigerant level checked for capacity..that is something you are going to have a guy w/gauges do. B/c your low fan are coming On by themselves , if the refrig level is low , it will only be slightly low b.c there is enough in here to trigger the low fan pigtail sw. [ a low on refrig system first sign is no low fan trigger ]

And lastly, b/c airflow has made a difference, I would clean out both the condenser fins and radiator fins with soap and a garden hose ..a car that old get full of dirt and air-flow restriction is your enemy. The a/c system can only take out the heat that the condenser can dissipate. The clener the cond, the cooler your car will be. and the cooler the temps will stay.

Most of this stuff is not yor Bag, but any decent guy could do these for you.
You could handle the cleaning of the cond/radiator and you could also do the blu sensoor mod if you had the ready made part. Both will help.
That's about all I can tell ya..........

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A Dalton

Arthur,
I jumped in a few posts back because I live near Ismalley and feel his pain. I had Jim F. make a special resistor that comes on at 88C and off at 82C. This keeps my engine temp just below 100C even at 115F ambient. Long ago I switched coolant ratios and use only a gallon of antifreeze, balance distilled H2O and "Water Wetter". Since I will never experience freezing temps, this is ideal.

While these things keep th engine cooler, I have noticed that in temps over 105F, the AC cabin temps climb. I use a thermometer in the center vent. While the cooled air is a lot cooler than the outside air, I no longer get 40F coming out of the vents. I have resigned myself to these facts. We try to run our errands in the AM before we hit 105+
Anziani
'93 300CE
'95 E420

< I have noticed that in temps over 105F, the AC cabin temps climb.>

Yeah, that's about all you can expect. You are maxed out. Live with it.
The only other tweaks are to use a slower blower speed and to Tint Roll the windows.

All other mods are big $$$ items ..

A Note for you and readers:
On the CTS bridging mod, one also has to be concerned with going too extreme with cut-in for fan. The reason for this is b/c that sensor is not just the aux fan control. It is actually the temp Input sensor to the ac Control Module N22, and that module uses that same input sig for compressor cut-off. So , it is possible to go so far that one can get a cycling compresor at high temps, thereby losing a/c capacity...just something to be aware of.
My preference is to run a relay using the low fan feed at the pre-resistor as trigger, and that allows me to have HIGH fan when a/c pressure sw calls for Condenser Fan. That addresses the cond/ac operation directly, and allows for high fan pre coolant temp esculation. You now have High Fan for a/c , regardless of coolant temp. And it is the condenser that drags down the radiator by passive heat exchange at High termal Load conditions...wish they had the condenser mounted somewhere else.
But none are going to ice you out of the car at 105 ambients..maybe fill the back seat with ice cubes ...

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A Dalton

Arthur,
Yes we have tinted windows and a 79C T-stat. Here is a website for "parallel condensers" over in Phoenix. Might be a possibility. They apparently offer installation.

http://www.ackits.com/merchant.mvc?Screen=SFNT&Store_Code=01

I would be curious to know how the newer Benzes ('98-2005) hold up at these conditions (105-120F)
Anziani

A/C systems are sensitive to temperature changes, and by speeding up the blower on the front of your condenser, you have changed the pressures in the refrigeration system. 134a sucks.

You might consider having your A/C guy check the condenser to be sure it is not clogged with bugs, etc.

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My first Mercedes Benz. 4/6/07.

1984 190E (201 024) 2.3L four.

Interesting thread. Read through it all.

Arthur -- I am unfamiliar with his engine, so for my M103, can I still trick the fans to kick in on high once the engine is up to operating temperature? The blue sensor would be the 3rd sensor from the back of the head, correct? It looks the same as posted earlier...but just want to be sure it will do the same thing before I started unplugging things while the engine is running.

Also just curious, why does the car have to be at operating temperature before unplugging it?

I am less than satisfied with my A/C performance as well and wanted to see how much the high aux fan would improve performance.
...well either way I'd like to do it as any boost would be great.
Do you happen to have a parts list needed for the correct resistor to get the system to run in high all the time?

Much appreciated. This thread made my head hurt overall. Sorry to bump it

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Getting high fan for the a/c uses a relay to by-pass the speed dropping resistor. Don;t confuse that resistor with the little resistor we use to lower the blu sensor. Lowing the blu sesnors value will not get you a high fan with a/c ..that is a different mod.

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A Dalton

Sorry, yes that is what I meant. Any parts list for the relay? I searched, but didn't find it. Only that it was "done".

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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

Radio shack has a nice standard 12V/40A relay for $6/7...

What you do is take the single wire off the R15 dropping resistor behind the headlamp and use that at a relay to trigger the relay [ term 85/coil]
Ground the other coil terminal to complete the coil circuit [ 86]

Now , use the power contacts of the relay [ 30 and 87] as a 12v power feed from the battery to 30 and 87 goes to the R15 2 wire side . Put a fuse in the bat feed line to relay [ 30A ] ...use heavy wire for this line..
That's it. Now , when the high side pressure sw at the reciever/drier closes and calls for low fan , that sig triggers your new relay instead of the dropping resistor, and the relay BY-PASSES that R15 ...so you wind up with high fan for ac instead of factory low speed...that's all.
All other circuits stay the same ..

Some guys just jumper the R15, but that fails real quick b/c the factory wiring for low fan circuit is too small to be running a HIGH fan/s current draw... see them burnright up ..[ but the addition of the simple relay/circuit will take that extra load/draw needed to run the fan/s on HIGH.]
You can also jumper R15... IF you double up the wire from the low fan relay to the single side of R15, and then put a high fan relay in place of the low fan relay. That is more work and cost, but also works.
Either way does away with the dropping resistor R15, which is what gives the fans their low speed.
If you are in moderate climates , low fan is adequate..

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A Dalton