a2aa, haasman, tkamiya:
First let me apologize for the slow response. I have been out of town for a week and without access to a computer.
Allow me to address all 3 posts.
1) I do not have a problem with temps getting to 100 on days I do not need the AC. I get to about 95 and that's about it. I have designed a circuit that I haven't yet implemented that will utilitize both the high and low speed fan relays and work in conjunction with the temp sensor much like the resistor mod located on another thread. In fact, I got the inspiration for the design from that very thread. In short, it will turn on the fans in low speed at a determined temp (adjustable), and then turn on the fans in high speed at a determined temp (also adjustable). I believe the newer MB models have this type of two speed control built into them.
One thing I did notice after changing the thermostat was that my temps run cooler than they did prior to changing the thermostat (82-85). It could be that the thermostat was marginal, but I rather think the lower running temps are due to the fact I replaced the coolant with a 40/60 mixture instead of 50/50. This of course should cause the engine to run slightly cooler with the reduced amount of antifreeze in the system. I'm sure you've read several discussions on this subject so I won't comment any further.
2) I would be happy to supply all the part numbers, as well as a picture (providing I can figure out how to do that), and will do that first chance I get next week (just got back in town and am going to the winston cup race tomorrow here in Charlotte).
3) Thanks for letting me know where the O2 sensor is. BTW, I bought a MB service CD last week.
To date I have not had any problems with the mod, and it has helped keep the car considerably cooler with the AC on. I live in Charlotte, NC and it gets pretty hot and humid in the summer. There's more that can be done, but for me, this is a start.
92 300E - 116K miles - Sold
77 Euro 350SL - 67k miles
94 Explorer 147k miles
2009 Hyundai Genesis - 65k miles