Arthur - what started this whole concern about the aux fan goes back about 30 days ago when I noticed they did not seem be coming on at all as the temp started to climb. I searched the posts here and came across yours from a couple of years back where you mention the #6 fuse, the possibility of blue and green relays being reversed in their socket position and the update for the 15A fuse on the low fan relay.

I did not have a blown #6 but rather the D fuse which also is on the aux fan circuit. I went ahead to check the relays and found they were reversed. I guess this was done many years ago when MB replaced the wiring harness. I repositioned them and changed out the 15A with 20A.

I guess I never had properly operating aux fans. Seeing them run constantly in this hot weather was something I was not use to and made me think I had a problem.