Attached please find two pictures - one is the open fuse box which looks different from your picture, and the other is the fuse description card which indeed shows the auxiliary fan fuse as #1.

What do I do from here?

Nobody has mentioned the infamous R15, auxiliary fan resistor.
This connection fails fairly often. It's a big ceramic resistor waaaaaay down in the fender well, sorta under the front right side of the fuse box, under the AC hoses and other wires. It's sometimes hidden by the leaves that collect down there. Usually the wires get corroded by the heat it generates and they fall off. Can be a fire hazard also.
R15 only comes into play on the fan low speed, which is turned on by the AC pressure switch, then routed through relay K10, to the input side of R15. But, the wire to the fans coming from relay K9 for high speed is also hooked to the output side of R15, and it could be corroded off.
I had to replace one last year.
Do a search under Auxiliary fan resistor for the exact location and wiring details.

Also, to check the actual fans, just find the wire plug right near the AC accumulator, and unplug the connector; then put 12V on the wire and both fans should run on high.

DG

Today I finally could get back out there to pursue this temperature problem, and checked the fans.

As suggested in a post above, I separated the two fan wire connectors. Coming from the fans to the male spade connectors are one brown wire and one brown with white. When I connect 12v to these male lugs, nothing happens whether the ignition is on or off (motor not running).

Those wires connect to the female connector, one wire brown and the other brown with blue. When I connected the 12v to these female connectors, nothing. HOWEVER when I connected the negative ONLY to the brown/blue, with the ignition OFF, both fans came on.

Sounds crazy to me, but does that mean the fans are actually working? I still don't like the temp being 85C as the normal temp, going up to almost 100C when stuck in traffic, and then (maybe the fans are actually working) dropping to a little over 90C.

Before I got the radiator flushed and the antifreeze changed by the dealer (at a high price) the car ran normally at a touch over 80C and at worst in traffic moved up to about 85C.

Thoughts?

Fans are working if they turned on. My suggestion is look online for "cool harness" to trick your fans to come on earlier but the right fix is probably your tubes in the radiator have scale and isnt as efficient and the thermostat is failing and your water pump is old so between the 3 you get higher than your used to temps. Once 1 part goes bad the rest start to follow suit as they help each other and are not redundant features.

When the engine is operating normally at ambient 85 - 90 degrees no fans are in operation. If the car is going over the speed of 30 kilometers an hour enough air should be drawn through the condenser/radiator to provide enough cooling for the engine system.

If in slow traffic or very hot conditions if the temperature passing the viscous fan reaches above 95 degrees then this fan will "lock up" and cause extra air to be pulled through the condenser/radiator. You can hear this when it happens, there is a fan roar when revving the engine.

The AC controls will decide if there is extra cooling required across the condenser and will activate the electric fan at low speed.

If the engine temperature exceeds 105 - 110 the sensor on the head will activate high speed electric fans.

There are two relays - one each for high and low speed electric fan operation. You can remove the relays and bridge the active contacts to ensure the circuitry to the fans is O.K. and to test the resistor that controls fan speed. You need a little bot of technical nouse to be able to do this.

Cooling also depends on the condition of the radiator, coolant level, leak free coolant system, proper operation of the thermostat and proper circulation operation of the water pump. The serpentine fan belt must be at the correct tension otherwise slippage of the pulley driving the viscous fan and water pump can occur.

Temperature rise and fall in traffic or hot days is normal. Sometimes I speculate wether or not MB should have put an idiot light in the instrument cluster rather than a gauge. - Keeps people from worrying about the rise and fall.

Except in extreme cases, if the temperature rises constantly above 105 - 110 degrees there is some case to worry. Last summer in my city there were three days in a row over 45 degrees Celsius (115 degrees Fahrenheit). The temperature on my M103 got to a constant 110 degrees driving on a freeway with both the viscous and high speed electric fans on.

Thank you for helpful thoughts.
I'm paranoid because it is an older car and especially it DIDN'T RUN THIS HOT BEFORE THE DEALER SERVICED IT!!!

Check the coolant mix and make sure it is not too much glycol!! That will make things get hotter for sure. I only say this because you point out that you did not have this problem until the dealer service. Perhaps they forgot to dilute the coolant, and glycol by itself doesn't cool nearly as well as when mixed with water. A little $2 eye dropper coolant tester should tell you, though I've never used one with MB antifreeze. Anyone know for sure if they work with MB antifreeze?

For what they charged, they better not have goofed that up!
Will check tomorrow morning and post back if that is the problem.
Thank you.

I mean it's totally unlikely of course, but you were wondering what they could have possibly done to make such a difference, and there's not much more than that (unless they installed a hotter T-stat).

I guess it's also possible that the flush knocked some crud loose that is now plugging passages in the radiator or something.....

This is why I miss radiator caps that let you look down into the radiator!

Very hard to say without being there!

I took the car back and told them to test the thermostat to make sure it was not defective and to reflush the radiator in case they dislodged some gunk and didn't get it out.

Naturally they weren't going to do any extra work, so they told me they did "the research" and found that Mercedes now specifies an 87C thermostat (instead of 80) because if the engine runs hotter it is better for emissions.

Sounds like baloney to me, or at least that I should have been informed to make my own choice if I wanted a higher temp thermostat or not.

What would be the issue if the car failed the jumper test for the pressure switch? I hear the buried fan relay clicking but that's about it.