David, nice idea but a
lot of extra work just to turn on the aux fan(s) a little bit earlier.
For my car, for example, the following holds:
Aux Fan Switch Points: ===== 1st ====== 2nd ======3rd
Refrig Press ON (bar)[lbs] ==14 ===17 === 20 
So 206 lbs is very little pressure, so the Aux fan(s) start pretty much right after the A/C is started. I'm sure that your car is somewhat close to those numbers, so you went to a lot of extra work, $ cost and complication to turn the Aux fan(s) on a little early.
Very few people can sucessfully complete your results. I, as you know, make the Cool Harness, and what could be more simpe than that??? Then why do I have so many customers? And I have how-to-do pictures!
One of negative: Consider changing the relay to a more robust industrial grade relay for reliability. The 'weak' link in your design is that RS relay! If it fails, then the fans won't start! If you wan't my 'famous' RS story, let me know.
Anyway, it will do exactly what you wanted it to do, so enjoy!
Regards . . . . JimF
'94 S500 Cpe
Visit my Mercedes Web Page
Last edited by JimF; 10-15-2002 at 05:45 PM.