Well then let's get a happy medium -- I'll upgrade to the dual aux fan setup so that I can get a little better cooling and lower vent temps since it will cover the other 1/3rd of the condenser that the original one fan setup does not cover. I'll probably start a new thread for this since I doubt I'll get good responses hidden in this thread.

Thanks guys.

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ps,

As Jim said, he has lots of experience with these cars in stop and go driving in a climate almost as hot as yours. I don't have nearly so much stop & go experience, but it sounds like you're really in good shape with both the a/c and the cooling system.

I will be REALLY surprised if the marginal added flow from the dual fan will have much to do with engine temp. It will serve to bring down excessive high side pressure, but I really don't see it as the panacea you expect.

I admire your attention to detail and all the work you're willing to do for a hopeful gain, but as Jim says, I think you're obsessing a bit.

Best of luck with it. You live in a tough Summer environment and it sounds like, to your credit, you have the car in it's best condition to deal with it.

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

Annoy a Liberal, Read the Constitution

I think the dual electric fan & shroud setup is worthwhile.

In my experience, the '93 cooled better at around-town speeds than did the '87. There was no difference at highway speeds - both were fine.

While the '93 was a factory R-134a car and the '87 was of course R-12, the only two significant differences I ever identified between the ac systems were the dual fans & shroud combo on the '93 vs the single larger fan on the '87, and the compressor. The '87 used a Nippondenso 10p15 vs. the larger capacity 10p17 on the '93. BTW, the condersors are different part numbers, but the difference appears to be limited to the inlet/outlet port locations. Both pieces are basic serpentine condensors.

My experience is the condition of the system is more significant than any design differences between them. I got frustrated with a series of ac problems on the '87, so replaced everything all at once - evap, TXV, condensor, compressor, manifold hoses, dryer - everything. I used universal synthetic oil and charged it with R-134a. And you know what - it was fine in Dallas in July. Once convinced that it didn't leak, I recovered the 134a and charged with the proper weight of R-12. The only difference I noted was that it got colder in the first few seconds, but there really was no difference in vent temperatures or comfort. Somewhere back in the archives of mbshop there are a bunch of threads on my adventure.

BTW, just re-read through your thread. 39 is about as cold as it'll ever get. MB is very conservative with respect to freezing the evaporator. You are at or very near the point where the evap temp sensor will shut cycle the compressor. I think it is working just fine.

- JimY

Well, there you have it ps! It sounds like my comment in the other thread about going back to R12, might not hold water.

I don't know anyone with more INTIMATE knowledge of the 124 a/c system than Jim. I remember him at a dinner one night telling me about his entire a/c system rebuild. He knows the refrigeration AND the climate control system of these cars in detail and has experimented with different things.

You are the benefactor of the value of his findings.

I think that your success with your 134 charging was due to your using a small percentage of the specified R12 volume in R134a.

Best of luck with it.

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

Annoy a Liberal, Read the Constitution

Alright its time to act now and get better performance Got my bonus coming in next week which should cover all expenses.

My plan is following:

1) New 17cc denso compressor upgrade
2) R12 back conversion
3) New larger condenser

Now regarding the condenser....
--Will the large single fan "FIT" the later, larger condenser? I understand its designed for the dual fans, but I figure its not going to be any worse and I can do the dual fans at a later date when I find a car in the junkyard that has them. I can get ALL the clips, shroud etc and do it right. The A/C is not great on the freeway, if it was fine on the freeway, the issue would be airflow at idle, but since airflow is not missing, the issue lies within the system, so that is why I am not worried about the dual fan setup right now -- its just excessive costs that aren't justified yet.

So will that single fan fit? Anybody know?

Also, the hose locations are different...are these hoses generic ones that I could make work, or is this going to be a big problem?

So overall, I'll have a bigger compressor, bigger condenser, and more efficient R12 -- its GOTTA kick ass!!

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2003 Gray Mercedes ML350 - 122k

Someone on The Diesel side has done huge A/C upgrades to a W116 300SD. Very low outlet vent temps on R134. He has a huge effective looking electric fan up front.
His vent temps suggest it cools the condenser. My 88 300 TE runs 90c at speed
max A/C but will climb to 100c in traffic with R12, chilly inside 95f and humid outside. The original fans do not move enough air in traffic and block air flow at speed. Converting back to R12 will help, my 85 300SD with R134 does not cool the cabin above 95f. Hope this helps.

I am considering maybe getting one huge fan instead of the dual fan setup too, so that's why I also don't want to be forced to do the dual fan setup if possible.

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2003 Gray Mercedes ML350 - 122k

Hey Ps2cho, just wondering, did you try bypassing your heater core? You live in Arizona, I live in Palm Springs, Ca, so I know what the triple digits feel like, but try the bypass. Not sure if you have done this already, but it will literally take you 10 minutes to do.

1. Drain your coolant (make sure you have a fresh bottle to refill when done [Xerex-G05])

2. Disconnect both hoses that go into the heater core.

3. Use a long hose (I forget the diameter) to go from the engine block all the way around along the firewall to connect to the aluminum pipe that goes into the water pump. *Note, I removed the aux water pump and put a ball valve in place. I did this before I did my bypass because the heater valve broke and allowed coolant into the heater core still. After realizing I didn't even need a heater with year round temps staying in the 80s I did the complete bypass.

4. Refill the radiator with coolant and test ac out. I can almost gaurantee you will notice a 90% improvement.......Yes, 90%. I just did this same exact thing to my friends 2003 Nissan Sentra yesterday because apparently a valve wasn't closing and coolant still entered the heater core. He now gets -60F degrees at the vent!

Attached Thumbnails

 

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1990 190E 3.0L

I don't believe it would be an issue, but maybe I am wrong? I've always thought with A/C off my ambient vent temps seem warmer than they should be...but its hard to tell.

What about if I just replace the valve for good measures? I don't particularly want to rig anything. Should be an easy swap with a new one in hand right? Just clamp hoses, swap, reconnect. Maybe I should start with that before spending $400 on condenser/compressor/drier.

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2003 Gray Mercedes ML350 - 122k

please just try the heater core bypass. You have nothing to lose in doing it. If you find that it works, then guess what? You now know that your ac components are not the problem. Consider this a way to test your ac system instead of throwing parts at it. This will cost you no more than $20-$30 for hose and coolant and 10 minutes of your time. I swear by the bypass as I have already posted pictures of getting up to negative 40*F at the vent on my m103 with a r134 conversion.

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1990 190E 3.0L

You can't have a negative F temperature, that's 72 degree's below freezing point, but either way...

Money is not as much an issue as doing it right. I'll get the valve ordered so we can rule it off. Either way I still plan to back convert and do upgrades. I see it this way -- the ONLY thing I dislike about my 300TE is its ability to cool out here in Arizona summers. I'm not spending $20k on a new car to get cold air. I'm okay putting $1000+ towards getting the system back to factory condition or better.

I cannot imagine that a brand new 300TE off the floor in 1988 had the driver and passengers sweating in their seats as they test drove the car in 100F+ climates unless I am wrong and this was the norm for older cars back in the late 80's early 90's.

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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

Your coolant temps seem about right. There is a 79°F thermo that may help drop you a bit too. I use that along with the two row aluminum radiator, my temps in the summer with the A/C on here in Texas hover around 90°C. PO had a single core radiator and the car would hit 100-105°C pretty quick and stay there. It was flat out heat soaked. I wish there was a larger fan blade available to put on this thing, but my searching has come up empty sadly.

You also have to remember, for whatever reason MB chose to utilize a smaller radiator on the M103s which hurts cooling capacity.

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I'm not a doctor, but I'll have a look.

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Ordered AC + heater duovalve last night should be here Thursday I would guess..

Bought a mityvac 8000 this AM and tested all pods from glovebox -- took 10mins.
Looks like most of them are dead

That is probably not helping anything!!
Glovebox Out:

Main Line: Good vacuum

Pod 1: DEAD

Pod 2: DEAD

Pod 3: GOOD

Pod 4: Dead? Holds a small vacuum but hardly anything

Pod 5: GOOD

Pod 6: DEAD

Pod 7: DEAD


Out of time gotta run to work, but I'll find which pod controls what later and see if these dead pods are part of my issue

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2003 Gray Mercedes ML350 - 122k

That's REALLY bad news PS! Determine which one is bad. It sounds as if it might be the recirculate pod that's bad given your other symptoms.

I went through this about 8 years ago. In the process of it I got some of the nice aluminum tape and sealed off the cowl air intake thinking I could make for colder air until I could get to the podectomy. It didn't change anything, so I jumped on the podectomy and replaced them all. About a 15 hour job, but not complicated, just time consuming.

Buried somewhere in the bowels of this forum is a post identifying which port on the switchover valve is which. I'm sure you can find it in the FSM. It is tedious but possible to replace the defrost pod without removing the dash. If it's any of the others, don't even dream of replacing only the bad one, replace them ALL.

I hope this is not what you have run into.

Best of luck

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

Annoy a Liberal, Read the Constitution

Good progress! Each vacuum line is color coded to indicate which function it controls. We can dig that information up if you post which ones leak down. It's been posted before, but I can never find it using search.

However, given that you have many leaks, I expect you would be well served by a total pod-ectomy. I refer you to the GSXR/Dave mega-thread on 124 vacuum pod replacement...