It was great to stay cool in the traffic jam on the NJ Tpk yesterday on my home from New Brunswick NJ. There is always a jam where the truck and car routes converge. Usually I had to sit and watch my temperature climb to about 105 degrees before my high speed fans would kick in. Not anymore, since I have the Cool Harness V2! The fans do seem to stay on, once they are triggered at 95 degrees, but that seems much better than waiting to see 105 degrees. The reality is that if it is a hot day, the fans would have had to come back on again anyway. I suppose it is OK that they just stay on. I can't hear the fans at 80 miles an hour anyway. I think I would rather pay to replace my fan motors some day than run my car back and forth up to 105 degrees. Maybe now my head gasket leak won't get worse too fast. The car never went over 95 degrees. It was usually about 87 degrees when moving, just as it is supposed to be.

Anyway, I am a happy customer with my Cool harness V2.

Thank you JimF

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I just couldn't give up on my 1995 E320.

I think it might be like always going back to that same bad relationship with an ex girlfriend.
You feel you love them too much, or you are just too stupid to know any better.



Flickr slideshow of my 1995 E320
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Going back to Arthur's explanation of the HIGH and LOW fan systems, imagine this scenario:

- You have the manual switch in place but it is in the OFF position.
- Your A/C is OFF.
- The car heats up in stop and go traffic.

Will the HIGH fans still kick in when the car gets hot enough (105 degrees, I presume)? It would make sense since the HIGH and LOW fans are on different circuits, however, I am not sure if installing the manual switch puts it on the LOW fan circuit only.

Also, since the Cool Harness was also mentioned:

Does the original Cool Harness have the same problem as the V2 -- keeping the fans on HIGH once they are on? Is this a consistent problem with Cool Harness users or an isolated incident?

I am interested in applying both changes to my '89 190E 2.6 which has a dead A/C (leaky evap).

The hysterisis for the Aux Fan ckt is around 5 degs C; so if it goes on at 100C it should go off at 95C. Those MBs with multiple fan speeds have a slightly larger hysterisis value (on=115C; off=107C) at higher engine temps. All of this info is in MENU#18 in the "Aux Fans Activation".

If your car has dead A/C then it shouldn't get to 100+C; suggest that you follow the steps in MENU#17 in the "agua" colored table. The 5 steps should lower the engine temp so that the fans won't run all the time.

My car with A/C in 95F w/ 80% RH, doesn't go above 95C. On the highway, it's under 90C. So the A/F are off.

If the A/Fs don't go off, it's b/c the engine temp doesn't lower when the fans turn on, indicating something isn't right. The Cool Harness doesn't KEEP them on, your engine temperature does!

Also the original Cool Harness comes in three (3) ranges as shown on the CH table. I use the CH-92 but many prefer the CH-95 and/or CH-98. The numbers represent the trigger point for A/F cutin.

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Regards . . . . JimF
-------------------
'94 S500 Cpe

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Jim, thank you for the clarification. It makes sense now.

My car also stays below 90C on the highway. In stop and go traffic without A/C and roughly 95F ambient temperature, I have seen the auxiliary fans come on several times during the last 2 weeks or so. It looks like they engage at around 105-110C. It is a rare occurrence and the car cools down quickly with the fans on, but having them engage earlier will give me some extra peace of mind. CH-92 would be my choice as well.


Update from 8/26/07:

I installed the Cool Harness today, went with a CH-95 instead. It works flawlessly. Fans engage at 95C and go off at around 87C. This is awesome!

Guys

I don't mean to takeover this thread, but I have been reading quite a few since my temp gauge went to 120+ in traffic a couple of days ago (ambient temp was 32C or about 95F). I tried to get the fans to come on by turning on the A/C but they refused, so I managed to lower it by turning down some side streets & getting some air through the radiator.

A/C works well & the belt driven fan clutch was renewed last year & seems to be working OK.

I've tried to do some tests and so far today (35C) I have had 1 fan come on high at about 95-100C with the A/C on a short trip (right side looking at it from the front - your driver side).

Later I removed the Temp guage connector (which looked a bit beaten up) and the same fan came on high, but nothing from the other one.

When I bridged the plug I heard relays switching near the fusebox & near the A/C drier but no Low fan came on - in either of the fans.

I also tried bridging the each side of the Low fan resistor with 12v - but nothing happened with either side fan. Though I may not have done this correctly?

Does this mean -
I have at least 1 fan that's dodgy;
I possibly have a Resistor that's stuffed;
Possible other problems...

Any help greatfully accepted.

PS - something else I was wondering is that when all of the R12 was replaced with R134a a few years back, how does this affect the psi readings from the A/C for the Low speed fan? Are they close enough?

Cheers

Stu

Is this a double post?

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A Dalton