I researched back through some old posts and found where gsxr explained there are as many as four temp sensors on the 603 in different locations depending on year and model. On mine, the two pole switch is actually the afterglow temp sensor to the afterglow relay on one pole and the other pole goes to the interior temp gauge. The other (single pole) switch on the water outlet is for the Electronic Diesel System sensor. The auxiliary fan/AC protect switch should always be a 3 pole switch, in mine behind the IP with little to no access.

The car always runs hot, between 100°C - 115°C in ambient temps above 85°. I did find an aux fan burned out and the other feels bad (both original) so I am replacing both. And while they are out, I was able to flush 15 years of all kinds of debris (6 species of slow flying creatures) out of the condensor and radiator. The flush work alone lowered the average temps by about 10°C without the aux fans.

With the new fans I expect more improvement but I don't want the temps to go as high as 105°C to engage the fans. One of the old posts talks about a modification to the temp switch harness using a "cool harness" addition with an embedded 1/4 watt resistor to trigger the aux fans to engage at a lower temperature. Has anyone used this modification? I found more info about it at the inventors site [URL="http://pages.prodigy.net/jforgione/MB_S500.html"] and I contacted him to confirm its real.

Thoughts?

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2001 E320
1991 350SD 265,000 - SOLD
2000 VW Beetle 1.8Turbo - restored
1997 E320 - SOLD
1988 190E - SOLD
1969 Mustang - SOLD