E320 1995, Station wagon heating up? - Page 2 - PeachParts Mercedes-Benz Forum

cphilip · #16 12-30-2008, 07:30 PM

Got it. Will reread that a couple times to be sure but sounds like I am jumping the gun because I could not make the fans come on today.

Alright. Will have to locate these things and verify them all to be sure. I didn't see any bubbles in the Dryer window. Did look for that.

I am going to be taking the car to the Indy next week for tranny fluid (don't have a good place to do it) so I just might as well ask him to check the pressure anyway though. But by that time I should have a good weather day to do some of this other checking.

Thanks again Arthur.

Arthur Dalton · #17 12-30-2008, 07:36 PM

I say you are good to go.
You simply did not realize that the fans are only demanded when the system is being taxed.....many cars [ specially Asain] just have the fan come on with a/c regardless of ambients....so that is the general thinkings.
At least Benz knows enough to not have a system come on until it is acxtually needed .... so Aux actually means Auxilllary......as needed.

Gotta love that " High Termal Load " they use in the service manuals....

Added note**

You may want to print out the mentioned test procedure for low fan circuit integrity jumper for future possible No Low Fan condition....it is a great time saving test as it seperate the fans electrical components from a/c systems pressures for easy diagnosis in 15 second flat....good info.
..and while we are here , the High fan also has an easy test I use for verification..one simply unplugs the blue two wire coolant sensor and the high fan should come ON..the reason for this is b/c the Control Panel has a default setting that turns the fan on high in the event that a break or bad sensor condition presents ,,,that way you do not blow an engine b/c of a bad sensor or opencorcuit sensor...pretty cool of them....

The only trick on this one is if you do in fact do the resistor mod, then this test will not work b/c the bridge resistor is still in the sensor circuit in Parellel to the sensor, so the ECU does not see this as a bad sensor or open sensor,,thereby voiding the default test.. so, pay attention guys w/mod.

cphilip · #18 12-30-2008, 08:08 PM

Well I have to admit I have gone back and forth on what I believed on this. Partly from some erroneous information I read. First when I was shopping around I believed it did not come on until some point of demand. And so I attempted to tax the system until I saw it on each car I looked at. Appears I was on sort of the right track then. However I rarely was able to tax any of them to the point the high speed came on. In fact this car, I could only do it once I had run for about 130 miles of Interstate at 65 and 70 MPH on a 70 degree day and then pulled in the drive way and let it sit there and idle, in full Sunshine and closed up and Temp set all the way low to keep the AC on for well over 10 minutes. I went in the house for a few minutes an came out and the lows were on. I don't know exactly when but I peaked in through the window and it was at about 100C by then. And after another good long while (5 or so more minutes) it finally did go into high. Peaked in and it was right just about at 107C. So I thought, well... GOOD. It's working. I wait and watch for another like 5 minutes to be sure it will not continue rising. And it doesn't. It doesn't drop a lot but it doesn't rise. So finally I get in it and take it for a drive and let it cool back down and park it. Smug in the assumption I got a good one! hehe... But... thats a fairly crude test and I am, of course, just learning these 104's so I am not that confident.

Then I was reading some other threads where a posted exclaimed it should come on immediately. Well... like you say... I have seen many a car do this too. So I got to doubting myself then. So I went out and cranked it. But its a bit cooler today and its not had a hard run. So its not going to go over 82 today sitting there idling I guess. 20 minutes goes by and no fans. But still 82. So I give up and post that question to you because I notice you say, correctly, thermal load. I would have expected you to say "immediately" had you meant Immediately so I doubted this other sources information and wanted to clarify that. Because what you were saying is what I was seeing.

Thats the problem with internet information. You must be very choosy and careful what you glean out of it. And who you take it from. Eh?

I do still think I want this thing going into Turbo mode at 100C though. I don't see any real downside to this.

Thanks again Arthur. When your passing by from Florida to New Hampshire some day, take I-85 that time, swing off exit 14 in South Carolina about three miles and stop by for a cold one.

Arthur Dalton · #19 12-30-2008, 08:28 PM

>

I agree that the mod is a good one if one lives in Southern climates. Otherwise, the low fan cabin is sufficient.
The chosing of the correct R determines the cut-in ...everyone has there own preference , but I take all factors into consideration and have found that cut-in of 100c is best, b/c cut-out will naturally be lower. And if you have a lower cut-in, then they are going to be useing the fans way too much [ and not really needed]...so, fan motor longeveity is sacrificed, along with allt draw,etc....
The other problem is if one goes too low, they inadvertenly also lower the compressor cut-out spec.. What guys do not realize on this system is the fact that the same temp R output signal is the temp input for the a/c Control Panel..and the CP uses that SAME temp input not only for high fan activation, it also uses the same signal for comp cut-off control in the event of high over-heat...so, you have guys with a nice high fan ,but at the same time, they have NO ac if the temps climb just a little b/c the comp is cutting out b/c they fooled the temp input to the CP TOO MUCH... I had one the guy kept complaning of the cooling going OFF..guess why...yup!!!
There is always another story..you gain here , you lose there.....
Again, R factor to accomplish 100C cut-in is a happy medium for both circuits on 124.992 104 systems..by experience of many, many , mods.......but your preference. I do know these quite well.............

cphilip · #20 12-30-2008, 08:38 PM

Comment and provide any details you might have to accomplish this procedure you were recommending way back in 1999 Arthur... If you will...

For those interested in the manual over-ride cabin sw, ..the main reason for using the low fan circuit vs high fan is b/c you just have to hook your toggle ACROSS the high side pressure sw to make it work. This is as simple as it gets and there are 2 distinct advantages to using this point in that circuit for the switch ...the first being that you are still using the entire factory circuit
for fan activation [ minus the high side sw], meaning you still have a relay circuit and the protection of both the relays coil side fuse and the fans load side fuse...they are already there , plus the R15 Dropping resistor .... so this jumper/toggle uses the stuff that is already there ......you just add the switch....... The other nice about this is that when you are NOT using the manual switch, your fan circuit is right back to STOCK FACTORY confiquration..no change at all...that is why I refer to it as a low fan system OVER-RIDE vs just a manual low fan circuit. You are simply over-riding the pressure switch b/c you are in parrallel with it. The rest of the circuit could care less....

This is of great interest too. Particularly in conjunction with the resistor to have High speed cut in a tad early too.

Arthur Dalton · #21 12-30-2008, 08:45 PM

Yeah...that is just a detailed discription of the advantages of the cabin sw over the R mod.
If you go back to our earlier post, you will see how I mentioned just running a two wire cord to the High Side pressure sw at the drier...[ where I have you jumper for the low fan test] If you then run those two wires thru the firewall and hook them to a simple SPST toggle sw, you have low fan anytime you flip the switch..most guys just mount it under the dash...the advantage is you are using all existing circuitry/relay, and fusings, so you have the stock set-up when you are not using the sw..both of best worlds ... it simply lets you OVER-RIDE the existing low fan system anytime you want too...like when you are just hangin' out down at the lake with the GF.....

" Wait a sec Hon, we need some low fan here ....shes creepin' up on us....
I'll take care of it "

Oh, you'r so smart, Dear.

" Yeah, I know....."

cphilip · #22 12-30-2008, 08:53 PM

I might just do that. Seems easy enough. So, let me be sure I got this straight. Just T in a wire, one to each leg of the Dryer switch (total of two), and join them at a switch in the cabin and then open circuit (switch off) would be no activation of fans and closed switch would be activation of fans on demand. Peasy!

Arthur Dalton · #23 12-30-2008, 09:02 PM

Yeah,,that simple...........Hard for me to realize I wrote that almost 10 years ago...I've been here too long..... see 'em come, see 'em go..........

Many years ago [ when I was a kid] I had a new 250/8 and the aux fan on those was real loud, but it was a coool loud..almost sounded like a jet turbine spooling up...
Anyway, most of my friends were all motorheads and had some cool muscle cars, so I would pull in with the Benz and hit the switch for the high Fan [ they didn't even have a low fan then ]...and watch their heads spin around... they would ask what the hell you got in there ... ???

" Dual Turbos, Man...."
'Course , they didn't even know what a turbo was back then, but they knew "dem german cars" was GUD....