ac condenser design causing car to run hot? - PeachParts Mercedes-Benz Forum

TurboSDL · #1 06-02-2009, 12:15 AM

iv been doing alot of thinking on why my car tends to run hot somtimes, sure my gauge isnt perfectly accurate but i noticed somthing the other day, my ac isnt charged or working BUT, the fins on the ac condensor are vertical and the fins on the radiator are horizontal. this would definatly have to cause some kind of restriction in airflow, id be willing to bet if i remove the condensor that my operating temps will stay normal, or if i was to replace the condensor with one that has horizontal fins. my car tends to run slightly hotter when i am going like 80+ mph more like 85 and somtimes at idle... after i do a evac of the system and if there are leaks then i will remove the condensor and see if i get any better results.

TylerH860 · #2 06-02-2009, 03:36 AM

Where are you able to go 85 MPH? I seem to recall a few stretches in Colorado or Utah where the speed limit was 80 during my cross country road trip in my '85 300D. I noticed no change in temperature at 85MPH sustained speed, but the outdoor temperature was lower.

I would imagine that as long as it doesn't approach and sustain near the 100* mark during the run you should be fine. Approaching 100* at long idles on hot days is normal for these cars. They are not always going to stay pegged just above 80 all the time.

Removing components of the AC leaving open ended hoses to collect dirt may create problems should you ever decide to revive the AC.

TurboSDL · #3 06-02-2009, 05:31 AM

on i 65 going up to indiana i am doing about 80 85 for a good amt of time, even on the way to school in the morning on illinois highways the speed limit is 55- 65 but alot of people go 80+ and the temp gauge goes up to abt the 100 mark... good note about getting dirt in open ac lines, i was planning on putting rubber nipples over them tho or rubber corks in them if i would be taking the condenser out temporarily. either that or im going to put on electric fans

#4 06-02-2009, 07:42 AM

Have you tried a radiator flush? Replaced thermostat? Checked to make sure your water pump is okay? (i.e. shaft play, and make sure it isn't "weeping") I personally would advise against electric fans as I see more potential "fail" points with that system. Or the simpilest have you tried to clean out your radiator from the outside. (i.e. spray the inside with a hose and see if any junk comes out the other side.) hope this helps.

Ohhh and I live in Indiana and yes I-65 (or I-465) does get very very fast in some places.

leathermang · #5 06-02-2009, 07:55 AM

I would go with Helpplease... be sure all the fins on both sides of everything you own are straight and clean....
typically if you survey the actual surface area 10 -20 percent are bent... if the bent ones on the condensor are offset from the ones on the radiator you are in the 20-40 percent range immediately... and bug build up over 20 years can be substantial.... it is hard to see and correct the damage BETWEEN the condensor and the radiator.... but certainly the first area to look at and address in terms of logic and low cost.

awsrock · #6 06-02-2009, 08:53 AM

Quote:

Originally Posted by TylerH860

Where are you able to go 85 MPH?

That's Chicago expressways for you! Although, ever since gas got "expensive" (i.e., last year, but still has it's lasting effects to this day) it seems that less people have been in such a hurry. Or, maybe it's because I haven't had to travel on those roads daily for 3 years

I'd say heating up at 85 mph is normal..that's pretty quick! Granted, the higher rpms will flow more coolant, but pushing a 126 with 121 hp at 85 is still going to be somewhat demanding on the engine.

dieseldiehard · #7 06-02-2009, 11:54 AM

Quote:

Originally Posted by TurboSDL

on i 65 going up to indiana i am doing about 80 85 for a good amt of time, even on the way to school in the morning on illinois highways the speed limit is 55- 65 but alot of people go 80+ and the temp gauge goes up to abt the 100 mark... good note about getting dirt in open ac lines, i was planning on putting rubber nipples over them tho or rubber corks in them if i would be taking the condenser out temporarily. either that or im going to put on electric fans

forget adding electric fans, that will not help at freeway speeds. My experience is there is no way a 123 turbodiesel with a proper cooling system will run much above 90C except driving up the steepest roads (think mountains!) on a hot day (like 90+deg). If your radiator is more than 6 years or so old its probably gunked up. A flush with acidic stuff might help but I would consider replacing it altogether if its old. I never worry about temp while driving 75+MPH on my 300TD's. I do worry while snaking uphill in the mountains behind a slow moving vehicle on a Summer day.

TurboSDL · #8 06-02-2009, 12:25 PM

i have replaced the thermostat, replaced the waterpump, i havnt really flushed the radiator, the old coolant that came out didnt seem dirty at all even tho i put in new coolant, the fan clutch has some resistance to it when you spin it with the motor off so it should be in good shape, i used a hose and sprayed the radiator from the from the engine side out, and the condenser. the radiator looks to be in pretty good shape , the car easily reaches those speeds, iv done 105 in the car just to see what it could do and it could have gone faster had i not been afraid of getting a ticket, but i do like to travel at speeds of 80 85 because when i travel on the weekends from the chicago burbs to my parents lakehouse in indiana its about 2 hours away and i dont like to crawl there.

it just seems to me that if the fins were both in the same direction that the airflow would be much better.

leathermang · #9 06-02-2009, 12:55 PM

Quote:

Originally Posted by TurboSDL

i havnt really flushed the radiator, the old coolant that came out didnt seem dirty at all even tho i put in new coolant,

it just seems to me that if the fins were both in the same direction that the airflow would be much better.

The old coolant did not seem dirty because it LEFT THE GRUNGE on the inside of the radiator....

You have already made up your mind that the cross fins deal is a problem... I suggest you just go ahead and switch out...

You would be better off matching the fins on a new radiator to the condensor fins... that way you have a clean radiator inside also...and you will not have to flush the radiator out.

pelon · #10 06-02-2009, 01:15 PM

i just drove from ABQ to Las Cruces sunday at 78mph all the way on cruise control with the AC on and the temp never got above 85. i think it was only in the low 90's so not real hot yet outside.
sooo, you may need to flush your system and get all the basura out of there and straighten your fins.
let us know what you find and what worked.
roberto

TurboSDL · #11 06-02-2009, 04:51 PM

ya i may try to flush it out. where can i buy the citrus flush other than online? is there anything else that works well other than citrus flush? i dont really want to spend 250 on a radiator right now if im not positive it needs one.

79Mercy · #12 06-02-2009, 04:55 PM

the dealer sells citric acid, I forgot the cost.

::matthew · #13 06-02-2009, 04:57 PM

I got my citric acid from the local bulk foods/food co-op folks

Haven't done the flush, though

dieseldiehard · #14 06-04-2009, 07:40 PM

I read somewhere that 1/32 in of scale in a radiator will reduce thermal transfer something like 50%. Its bad stuff.
I really think that this flushing bit is overrated, it is probably good practice periodically but if you have a radiator that is really gunked up, just a single flush is probably not going to get all the stuff out of the inside of those thin tubes. Now, realizing that the 603 is a hair trigger thing what with #14 heads on them and it has been said that this car has a cooling system that is marginal ~~~ I just recommend if your radiator is over say 10 years old it is quite justifiable to replace it w/ a new Behr then you don't worry on a hot day while driving along in slow traffic, uphill etc. That's proven to be the solution in my experience.
DDH

Scott98 · #15 06-04-2009, 10:14 PM

At 20+ years old its times for a new radiator. You've probably got a ton of calcium build up from hard water use that you can't even see. Furthermore, your radiator neck is prone to snapping at the upper hose. It's a good preventive maintenance measure to just replace it. A proper functioning cooling system is more than adequate to cool your car.

Scott